Much advice has been offered to newly arriving members of the Reagan administration.

Deep thinkers have told them how to run the country. Humorists and specialists in whimsy have told them how to adapt to the strange people who inhabit the Washington area, and to the bizarre tribal customs of the natives.

Take it from me, stranger: Some of the deep thinkers are worth listening to, but you must figure out for yourself which ones they are. On the other hand, most of the humorists and specialists in whimsy are involved in an unfunny joke, and you should not take them seriously.

They will, for example, warn you that people here are clannish, and that it is hard to break into the inner circle of The Establishment. Don't panic. It was no different where you came from. The Oldest Inhabitants always upstage newcomers.

You will be told that people here drive like maniacs, but that should reassure you rather than alarm you. You should feel right at home.

You will hear that the crime rate is frightfully high in the Washington area. And it is. But the city you just left also worries about crime, so don't look down your nose at us.

You will be hard put to keep up with out latest fads and fashions, but don't despair. It was the same in Hot Coffee, Miss., or wherever else you came from.

You will be warned that in every government office there are people who are lazy, incompetent and just downright hostile toward the public. You can believe those who bring you this startling revelation.

People in government are like people in private business. Some work hard and are unbelievably nice. They will go to great lengths to help you. And some are flat-out jerks. Just like back home.

Most of you newcomers will fall into two categories. Some of you will be the peons who do the work, and some will be the honchos who tell the peons what to do and fire peons for doing the wrong thing.

The peons will be the first to understand that Washington is really two cities. One is the official federal city where bigshots wheel and deal. The other is a series of bedroom communities where ordinary people live ordinary lives and try to perform their duties with all the skill, diligence and devotion to duty they can muster.

After a while, the honchos also understand this.

Our local super-sophisticates say that once people move to Washington they can't bear to go home when they leave office. They say people stay on here because they have been smitten with "Potomac Fever."

Horsefeathers! People stay here because they discover there is more to Washington than who wore what to which embassy's party. They find that although the residents of this area are just ordinary people, they are nevertheless as extraordinary a collection of ordinary people as one can find in this diverse land.

So: Welcome to Washington, stranger! Distrust most of what you hear about us and some of what you think you see and hear. We're neither as good, bad or different as we have been depicted. In fact, if you look closely, you'll probably discover that we're no more unusual than the neighbors you left behind when you moved here. Or, for that matter, any more unusual than you are. ENOUGH, ALREADY

Today is Jan. 29, dear bankers. By this time, we all know that new rules have permitted interest to be paid on checking accounts since Jan. 1.

Please do not assault our ears with any more commercials that herald the arrival of interest-bearing checking accounts with trumpets appropriate to Resurrection Day.

Please stop using exaggerated boasts that your plan is better than any other. Instead give us specific information. Do we escape service charges by keeping a minimum balance in our accounts or an "average" balance? Explain in simple words how you compute an average balance. What happens if the average or minimum balance dips below the level you specify?

State details clearly. Don't treat us like country bumpkins who are unaware that you pay us 5 1/4 percent on the money we deposit with you and charge 21 percent when you lend our money to somebody else. Just tell us the facts and refrain from insulting our intelligence. Thank you.