The bases of my power is based on the notion of borrowing the powers of a given deity. As with any magic, the spells you right yourself are the most affective. Research the deity's history and learn what you can about it, before you mix energies with it.
I'm all for experimentation, but take the time to research the historic facts about a given deity to make sure it is something you want to have inside of you. I have learned the hard way that borrowing powers usually leads to making a trade of some kind. No deity will give you something for nothing. In my case I gave my grandma's life for power without knowing what I was doing. The deity I called upon I thought was on my side, so be very careful.
If you really want to borrow a god's powers, I hope you have something you are willing to lose to trade for that power. In the time I was able to successfully trade for powers, it took training by that deity to learn how to use it. It is like being handed the nuclear football and not knowing the launch codes. You may obtain incredible power and feel it, but not be able to use it.
My advice is to build a relationship with the chosen deity if you haven't already. Use the given spell on this site as a template for your spell to write your own. This shows the deity that you are serious about your request. If you have friends who know about your magical path, have them note any changes in your personality, this part is very important, because deities often use us to carry out part of their agenda usually without our knowing it.