Ohaiyo Drifter San,
Hehehe, can only offer my opinion for Sin City and not BKK from my experience. I make the following assumptions:
1. Capital is around THB 2 million
2. Long term residence is required (Work Permit)
Most biz in Sin City is tourist related. The more easy and fastest way is to 'buy' over existing biz. Most of the biz are for take over due to "Farang returning home, Farang retired to upcountry or simply poor management". Most are bar beers, massage shops, laundry (dry cleaning) and restuarants which the Koreans has been doing this, whereas the Russians prefer to start their own Tour companies, properties and souvenir shops biz etc.
If your friend is Japanese, he might want to consider Chonburi or Bang Saen where the population of Japanese residents are bigger. There is one shop that specialise in golf equipment and the shop only have Japanese words, meaning they are not interested in non-Japanese customers. Same for Russians, many of them only do biz with their own people due to language barrier.
Now come the most important thing and tricky thing, for legal biz, you need a Thai name to form a partnership and company.
