doing business in japan

I already know a little about the differences in doing business in Japan and in the West. Things such as the 'balloon effect', not being too pushy or enthusiast when representing your company to a Japanese firm for the first time, taking the Japanese firm's president out for drinks etc. Basically, contrary to many western standards.

This, however, is only the theory I know of.
Say a western business man were to do business with japanese companies, how would he go about to make a good impression? Approximately how long would it take before a deal is made?

It really depends on what kind of company you're going to deal with, also what is your position.

If you're rep from a well established company the counterpart recognize, and the company you're going to deal with has experience in international business, it should not be so different.
But if you're going to appoach a very concervative Japanese who has never dealt with a company from a western country, you'll find it very different.

do people in Japan put on their suits even in the hot summer periods? june-aug?

When you say Western, don't you mean, most likely, America? Things are different in the rest of the Western world.In many European countries anyone wanting to do business with a company does not expect to make a sale on the first meeting. One will make a appointment with the company owner or C.E.O to "get acquainted" and schedule a future lunch if the vibes are right. One will talk very little about the company one represent but one will try to understand the needs of his/ her company. Being pushy, bragging about one's company or worse oneself are deal killers. Not that different from the way business is done in Japan. I remember one of my first clients: he "grilled" me at length about local history, arts and dogs (all the while his old dog was on my lap). One week later he asked me to come by and asked my opinion about...a couple of days later he asked me to bring a sketch and a budget. A handshake was our only contract.