Maryland Gov. Harry Hughes has lost the deep Caribbean tan he sported when the General Assembly's legislative session began three months ago. His eyes are tired now and his complexion has the normal pallor of a long, cold winter.

But when the clock strikes midnight tomorrow, officially ending the 90-day session, Hughes will have fashioned a new image for himself that goes beyond his faded tan: he will have won new respect in the General Assembly, which this year has approved most of his politically risky legislative agenda.

The low-key 55-year-old governor, criticized three months ago for being a political outsider who lacked respect for the 188 member legislature, is now perceived as a matured version of the awkward rookie executive who took office four years ago. In contrast to last year, when he was blamed for a chorus of executive embarrassments that marked the end of the session, this year Hughes is getting credit for victories on tough election-year issues, such as raising the gasoline tax, drawing up a tight state budget, and mapping out a workable plan for legislative reapportionment. The insults and jokes he endured in the past have softened to concessions that in 1982 -- finally -- he defied all odds and became "politically effective."

What has changed is that Hughes has learned to strike a balance between being overly detached from the legislative process and being overly involved. He has demonstrated a growing appreciation for the legislature and the needs of politicians, particularly in an election year. And although legislators agree that he has always shown good will and an interest in compromise, it was not until the past three months that Hughes proved that he could work out compromises and deals to his advantage.

"He changed certain outward actions to answer some of the criticisms he received," explained House of Delegates' Speaker Benjamin L. Cardin (D-Baltimore), who worked more closely with Hughes this year than ever before. "I don't think any one could say he had a bad session. He knows the legislature better than he did before. He has gained in sophistication."

Even Hughes' failures this year, such as losing a controversial gun control bill and mishandling legislation on interest-rate deregulation, are excused as predictable mishaps in an election year. Although few are willing to say that the smooth legislative session has assured his reelection, most legislators agree that now it would take a scandal or a serious political blunder to damage him politically.

"Now members take him seriously as a political actor, a political force," said Del. Nancy K. Kopp (D-Montgomery). "People are impressed that he took some decisive action and ended up with some victories."

Hughes' legislative successes, and his ability to avoid embarrassment on a number of potentially damaging issues such as the interest-rate bill and the auto emissions inspection program, are due partly to the election-year sensitivities of the heavily Democratic legislature.

"Members of the legislature who are, after all, politicians, were looking for signals and for reasons to say good things about him," said one House of Delegates leader who asked not to be named. "It doesn't help a Democratic legislator to make the governor look" bad.

Some legislators say that the governor succeeded on his top priority, raising the gasoline tax, because he received more help from Cardin, who killed the measure in the final moments a year ago.

"The gas tax was a resounding victory in an election year," said Del. Gerard F. Devlin (D-Prince George's). "It proves that when Harry Hughes and Ben Cardin are on the same side, Harry Hughes does very well."

The evolution of Hughes during the past three months, and the changed perception of him among legislative leaders, also is the result of a conscious strategy aimed at preventing a repeat of last year's legislative debacle. And it reflects the maturation of a governor who arrived in the State House with a mandate to be "different" from his domineering predecessors, notably Marvin Mandel, but who needed three years to learn how.

It was in those early days of being "different" that Hughes made political gaffes that colored his administration for much of his term. Legislators still laugh about the time that Sen. Frederick Malkus, a 31-year veteran of the assembly from Dorchester County, escorted the mayor of Cambridge to the State House to witness the signing of a bill that would allow lead-shot to be used in hunting, an issue of great concern on the Eastern Shore. Moments after their arrival, the governor's spokesman informed them that Hughes had vetoed the bill.

Now, legislators say, such missteps are rare. "I can't believe it," said Sen. Thomas V. Mike Miller (D-Prince George's), "but he called me up to his office this year to tell me he was going to amend one of my bills in the House. That is really a change; that never would have happened before."

This year, Hughes and his staff had an orderly strategy. It began with staff changes that brought in a press officer who pushed the governor to improve his public persona, a patronage chief who soothed legislators by consulting them about appointments for local jobs, and a replacement for former corrections secretary, Gordon Kamka, whose stormy tenure lent credence to suggestions that the Hughes administration was out of contol.

Hughes, like an adolescent trying to cope with growing pains, began to respond to a litany of criticisms that cropped up during his first three years, including his failure to define a political agenda, his amorphous public image, and what was perceived as a condescending attitude toward the legislature in which he once served.

"They (the legislature) wanted clearer signals from him than he had given," said one top executive aide. "There was a notion that he had better articulate what he wanted them to do. And on some of these issues he really has worked . . . "

Hughes began to outline his legislative program earlier than in previous years. Before the session started he spilled out portions of his budget, which the legislature uncharacteristically left intact, and announced his commitment to passage of a gas tax. His handling of the budget, his top aides say, set the tone for the rest of the session by weakening the prospects for legislative opposition on a normally volatile issue.

"We realized we had to start earlier," Hughes said yesterday. "I decided this was the year that I was going to get the gas tax out. I started early for two reasons: first, to make sure it would get out, and second, to make sure that no one could say I didn't get it in early enough."

Then, early on, just as legislators began to grumble that the sun-tanned governor had been in the Caribbean for a two-week New Year's vacation instead of preparing for a potentially explosive legislative session, he suprised them. He struck a clever political deal on reapportionment and departed from his staid oratorical style to deliver a forceful State of the State address that drew national attention because of its harsh criticism of President Reagan.

The reapportionment deal, which became public the day before the session started, placated the politically troublesome legislative delegation from Prince George's County, which since has become a reservoir of enthusiastic Hughes supporters.

"He created a lot of good will here," said Miller, adding that Hughes has promised to spend three days campaigning for legislators in the county. "There is no question that it was a smart political move."

Throughout the session, Hughes continued to surprise skeptics who had worried nervously about his ability to handle controversial issues during an election year. In January, he leaked results of a poll that showed him the clear favorite against leading Democratic challengers and Republicans, quieting detractors who were searching for a candidate to run against him. He invited legislators and their constituents to small dinner gatherings in the State House, reflecting a once-hidden concern for politicians in an election year. He has surprised legislators by making an unusually large number of trips to the State House cloakrooms for personal chats.

And he lobbied for his favorite legislation, intervening first on a bill to raise the drinking age, then on the gas tax, where he was willing to cut some deals to ensure its passage.

Critics mounted efforts to discredit and embarrass Hughes, but failed. His two chief adversaries, Anne Arundel County Executive Robert A. Pascal, a Republican candidate for governor, joined forces with Sen. Harry J. McGuirk, the powerful chairman of the Senate Economic Affairs committee, to publicize what they alleged was a costly and unethical auto emissions inspections program worked out by Hughes. The governor defused the issue, working out a convenient compromise that the legislature swiftly approved.

Now, some legislators say, there is even a growing resentment of the most vocal and persistent anti-Hughes group, led by Del. Paul Weisengoff (D-Baltimore), who used to win votes for issues simply by labelling them as ways to "get-Harry."

The legislators' salute to Hughes as a more ripened politician has not diluted impressions that he is a clean-government executive who shuns arm-twisting and overt wheeling and dealing. It does reflect a commonly-held view that Hughes, after four years, has finally grown more comfortable in what is for him an uncomfortable role.

"He's not a real sparkle-farkle," said Sen. Julian L. Lapides (D-Baltimore). "What can you do about it? You can't remake the guy. I'm just so happy there haven't been any scandals up there. That's a real plus."