My first spell was one off of this site; it was the chant to bring rain.
It worked wonderfully and I got the exact results I was looking for.
Although I had to chant the full thing 6-7 times before it ever worked.
Spells are not always going to work, and when they do it's not always the first try that does trick. Spells also, often take a while to come into effect and begin working.
Understand your spells and how they work, if you don't know what's happening then there's no way you're going to get it to work how you truly intended. You must also really want it to work, desire the outcome more than anything otherwise the energies in casting it won't have much of a guide-line to begin working. Then of course, believe it- know it will happen and put yourself in the mind set of it doing so; which is why visualization is so useful in so many cases, it helps you into the mind set of the spell working.
I agree with Nevermore as well- spell of your own work the best when you cast them.