It can help you, but if you're not qualified for admission under regular decision, you are also unlikely to get in early decision or early action. In general, it will not significantly boost your chances, but it might help a little bit, and it will also obviously notify you earlier (which may be nice if you are admitted, because you'll know sooner).
In general, you should not apply to a binding early program (i.e., where you have to go if admitted) unless you're sure it's your first choice. It's definitely not worth it to get in and then realize it's not what you want. Also, if you really need a strong financial aid package, sometimes when you apply can affect the aid options you get from different schools; talk to your college counselor about this, as I don't have much information on that.