I can certainly go on record stating that i have found many benefits in my own life through the working of magical spells and that here in our shop we have had many customers provide us with feedback that they have had successful results with spell=craft -- but due to the nature of magic and the differentiation of attention and power among those who employ these spells, combined with the irregularity of feedback, we cannot be absolutely certain of their success rate.
To practice magic wisely, you need to be aware that not all spells work for every person every time. Like sports contests and wars, there may be a winner and a loser ... or, as with farming, some crops may thrive while others fail. You do your best and try to get the results you want with all the knowledge, dedication, and will-power you can bring to bear on the event -- and if you win, it's a triumph, and if you lose, it is defeat.
Magic is no different than any other area of life in this regard.
What i tell my customers and clients -- and you, the reader of this web site -- is this: Even if you use magic only to concentrate upon your desires and to pray, you will at least have clarified what it is you want. If it works for you, however, as it very often does, then you will not only have clarified your desires, you will have achieved them.