Choose broker which offers low spread and low commission is highly preferred for beginners. Otherwise high charges or wider spread eat up the portion of profit and leave it little added to your account in the end. Also consider the swap charges (for overnight positions) as well. Make sure it experiences minimal slippage.
Well, here is the thing, You need to learn as much as you can about the market and brokers before start. I recommend to deal with only reliable brokers, do not forget there are plenty of bad eggs everywhere. I have been working with City FX broker cityfxbroker.com and pretty satisfied both with their service and my income.