*Almost* any spell has the potential to work. The question is, do you know how to work it?
If you are failing at spells, then the answer is no. There is much more to casting a spell than lighting a candle and reading a few lines. All that is, is reading poetry by candle light.
You need to understand how to feel your energy, focus it, control it, send it out, ect.
You also need to be aware that without the right focus, and something even with the right focus, spells work in ways we don't want or expect them to.
Until you know these things, spells will not work for you.