@rd,
The general rule in picking a broker is Regulation, Location, Funding Option.
Pick a broker and check if they are regulated by a reputable organization such as CFTC, NFA, FSA to name a few. However, some regulatory bodies are useless.
Some brokers might list on their website that they are regulated with matching membership number to boot. Yet, when you investigate, this membership belongs to some long dead broker company, or to some individual or their membership has already been pulled out.
Next is the location: do not transact with brokers located in sleazy countries. GO with the mainstream.
Next is the funding options: though most brokers only accept wire transfer, some will accept paypal/creditcard and the like. these instruments provide some safety to you in the event that the broker tries to scam you.
Last of the list is the execution of the trade. Some brokers are OK, while some are slow. pick your choice.