^Excellent advise above.
Personally, there is no ''one way'' to energy, and it can come in a variety of forms. From spirits, meditation, leylines, psychic vampirism, etc.
Find one that appeals to you, and do it. Regularly.
See how you can exercise and get more power as well. Magical power is simply how far you can push in one direction, or another, or another...
Entities with more energy than power are ''fat'', whereas those with more power than energy, are ''sparks''. You want to be balanced, though with slightly more power than energy.
Energy comes naturally, though, but is wasted too much, on things like self-importance, addiction, etc. so to be rid of those things, I would advise learning how to eliminate them. Having enough energy saved is called, in Castaneda terms, impeccability, and you can read about it in those books.