President Reagan surveyed his mountaintop California ranch today looking for summer vacation projects while his aides plotted a fall political and foreign policy strategy from their oceanside hotel here.

White House spokesman Larry Speakes announced that senior officials would hold an unusual long-distance telephone conference call session Tuesday with other aides in Washington to discuss autumn plans.

Unlike most staff meetings, Speakes said, reporters and television cameras would be invited to watch the opening moments, a "photo opportunity" showing the White House staff at work.

Speakes said the strategy for a fall effort would be put into a written plan and delivered to the president by week's end. White House officials are accelerating their planning for a Reagan "offensive" on budget and tax issues after Labor Day.

A senior White House official also said here the plan would look ahead to the 1986 elections and Reagan's role in helping keep GOP control of the Senate.

Reagan used the first full day of his three-week summer vacation to walk about Rancho del Cielo with Nancy Reagan, looking for summer projects, Speakes said. Recuperating from cancer surgery, Reagan did not go horseback riding today, spending the morning on paper work.

The president has put off until later this month a decision on footwear import protections, Speakes said, and is planning no official visitors. Reagan is also reading material to prepare for November's summit meeting with Soviet leader Mikhail Gorbachev, Speakes said.

The fall "offensive" on domestic policy issues picked up steam last week in the wake of a series of congressional setbacks for the president, including a budget resolution that drastically reordered his spending priorities, and reports of higher deficits than previously predicted.

Speakes said today that Reagan would devote the autumn months to fighting additional spending in Congress, seeking public support for his tax overhaul plan, preparing the fiscal 1987 budget, battling trade protectionism on Capitol Hill and preparing for the Gorbachev summit.

He said Reagan would use the same techniques for advancing his policies as he has throughout his presidency: television and radio speeches, meetings with groups at the White House and travel around the country.

Reagan "will be vigorous, healthy and able to travel around," Speakes said.

As expected, the White House today announced appointment of new assistants for politics and legislative affairs, as part of the accelerated fall planning. Mitchell Daniels Jr. was promoted to succeed Edward J. Rollins as political director and M.B. Oglesby Jr. will assume responsibility for congressional relations, which he has shared with Max L. Friedersdorf. Both Rollins and Friedersdorf are leaving.