It depends upon you. If you are a sole proprietor, it should be registered with registrar of firm as sole proprietor. If you are more than one it should be registered as partnership firm before the same registrar of firm. Under this category there will not be much accountability to the Government.
If you want to establish as pvt ltd or public limited company, it should be registered in registrar of companies. Under this catagery there will be lot of accountability to the government. Private limited is of your own funds, whereas public ltd is collection of your funds and public funds.
Regarding the taxes, sales taxes i.e. APGST, CST, Municipal permission etc are required.