TOKYO, JAN. 8 -- Japanese Prime Minister Noboru Takeshita sought to lower expectations today for his first meeting with President Reagan, which is to take place next week in an atmosphere strained by trade tensions and the dramatic decline in the dollar.

Takeshita has prepared several omiyage, or offerings, designed to smooth his way during the visit, including an increase in funding for U.S. military bases in Japan and possible compromises on one or two trade disputes.

In briefings this week, Japanese officials portrayed the U.S. visit as a goodwill trip designed to establish warm relations between the two leaders, rather than to settle specific trade issues that have soured the Japanese-U.S. relationship of late.

"This is not for negotiation. We'd like to have the start of good personal contact between the two leaders," said Foreign Ministry spokesman Yoshifumi Matsuda.

For Takeshita, who became prime minister two months ago, the U.S. visit poses some risks: domestic politics here require that a prime minister show he can work well and as an equal with Japan's key ally and trading partner. Takeshita's predecessor, Yasuhiro Nakasone, achieved unusual popularity by appearing forceful at international gatherings.

Despite having served as finance minister and in other high-level posts, the low-key, self-effacing Takeshita is almost unknown in the United States, a problem Japanese government officials said they hoped next week's trip to Washington would rectify.

Takeshita said in a meeting with foreign correspondents today that the goal of his trip was "to make the Japan-U.S. relationship even more unshakable than it is today." He is also determined, he said, to show that Japan is willing to shoulder greater international responsibilities commensurate with its wealth.

Takeshita's trip, which includes a visit to Canada, comes at a time of uncertainty in world financial markets. The recent dramatic falls in the value of the dollar threaten to erode Japanese competitiveness as an exporter. Takeshita said today that it is necessary for the United States and Japan, which together account for a third of the world's production, to cooperate closely on economic matters to "realize prosperity of the world as a whole."

Takeshita said he had prepared no specific agenda for the meeting with Reagan next Wednesday, but hoped to cover a wide variety of global and bilateral matters, including Japan's efforts to reduce its trade surpluses with the rest of the world by reorienting its economy away from exports.

The prime minister said he expected that meetings between Secretary of State George P. Shultz and Japanese Foreign Minister Sosuke Uno would deal in more detail with some of the trade disputes, including the lack of access for U.S. construction firms to Japanese public works projects and Japan's closed agricultural markets.

Officials here said Japan will propose possible compromises in both areas. On the question of lack of foreign participation in public works, which recently caused retaliation from Congress in the form of a ban on Japanese access to U.S. public works projects, officials said Japanese construction companies would offer to set up joint ventures with American firms to allow them to participate.

Japan also will make it known that it will accept a recommendation by a panel of the General Agreements on Tariffs and Trade that it lift quotas protecting 10 agricultural products or offer compensation by lowering tariffs on other products, officials said. Last month, Japan in effect spurned the recommendation.

U.S. officials familiar with the Japanese proposals described them this week as acceptable but "nothing dramatic," as one put it. They were more enthusiastic about the decision, announced today, to double by 1990 the $150 million that Japan will pay this year to help cover the nonsalary costs, such as retirement pay, bonuses and commuting costs, of 21,000 Japanese working on U.S. military bases in Japan.

Nakasone, before stepping down as prime minister last October, had said Japan would increase funding for U.S. forces in Japan as a round-about way of contributing to the U.S.-led effort to ensure safety of navigation in the Persian Gulf.