I use etrade.
https://us.etrade.com/home?ploc=p-Logo
There are many different plans for how you plan on investing. Go to the site and do the surveys it will help you out.
I also use a private broker for some trading. Not all stocks are on the exchange and sometimes it's easier for me to use a broker when I'm not going to be at home due to work. He can watch my stocks while I'm at worked make trades as per my plan. Costs more but saves me money in the long run.