Large caps are not really the best for day trading. Too sluggish. But be it large, medium, or small,as long as the stock is active and with sufficient volume, it qualifies. Rather than picking from a list of stocks such as the Nikkei 225, traders usually select active stocks and create a watchlist that they follow and then trade stocks from the list once the stock works into the trader's setup. If you want to do it that way, you might be better off using Kabu.com's KabuStation rather thanSBI. You can open an account online in one day and then apply for the margin account you wanted the next day. But say on the application that you have over 1 year of experience trading on margin. However I don't know if they'll approve it as you are a student.