As a newbie, there are many factors which one should look for in a broker like you might want to look at the reputation of the broker then leverage, tight spreads, execution speed etc. However, to check this, demo account is not gonna work, you need to open a real account. May be you can start up with a micro account. To start with, I think Turnkey Forex would be nice. They are pretty reliable and reasonable when it comes to trading conditions and services.