to legally "day trade" you need to have $25,000 in a brokerage acct - any less and you will be limited to teh number of transactions per week you can do - SEC laws
Best stocks to day trade are the ones you are very familiar with. You need to study the stock: what are the normal chart patterns and what are the catalysts that could cause it to make an abnormal move. Pick some you are are already familar with and watch them daily. Don't rely on tips. Tips are usually given with an ulterior motive.
Shorting? Unless you are very good I would advise against shorting in a strong up market. You could easily get hurt and face a margin call.