Don't lust for results. As hard as it may sound, after you cast the spell, try to forget about it. Go about your days like normal. The more you think about it, you'll worry about it then hope for it, wonder...then doubt...then fear the doubt and worry is true. And all you are doing is foiling your work. So once you have resolve in what you're doing, get it done, and get on with life. When your results come, then you can celebrate and give thanks and think about it all you want to. =P
You don't need luck, you need to be relaxed. You don't need to believe or be confident, just relax and get it done. The confidence and belief will come later.