Since you speak English and Spanish you have a good base to help you with French. The common latin base for all three will help a lot -- although English lost the concept of sex for inanimate objects, which is one of the harder parts for anyone learning from a purely English start. Spanish will have you familiar with that.
The real way to do it is to live in a French speaking country (same applies to any language).
Not only does this force you to use the language, but you hear and pick up the accent -- and believe me, accent is a BIG part of being understood in French.
Getting to the point of being able to communicate is not hard. Getting to the point of being really fluent will take more time.
I learned French in France. My boss at the time was English -- I asked him for some advice on becoming more fluent. He thought about it, and said theire are basically two ways: One is to buy a TV and watch a lot. The other is to get a French girl-friend.
I thought about it for a while ... and decided the TV was cheaper ... and safer ... if my wife ever found out