I have noticed a lot of people who used to practice occultism are now against it, saying it doesn't work and it's all in our heads. I have already written an article about the psychology paradigm and its pitfalls so I would like to link you there. For the rest of this article I am going to write a set of conditions you should follow for your practice to have fruits.
Keep a journal
I have written this over million times now, yet some people still don't get the hint. Journal helps you to remember things better, track your progress, track your results for later analysis AND it gives you important stimuli for times when you are in doubt. A journal is a must for every occultist.
Also, if your operation goes awry, write it to your journal as well, for example if you mispronounce some name, if you forget some move or simply when you are just not feeling it, write it all down. That way you will get doubts out of your head and later when checking results you can say: "Ok, I didn't do A and B and the operation failed" or: "I forgot to do A and I did B instead of C, yet the operation worked, so A and B might not be as important".
People who quit Magick tend to have very intense, but shortlived practices. Hours of meditations for practiced for 1 month at most. It is better to meditate daily 5 minutes for a full year than meditate 2+ hours for 2 weeks. Steady practice is really important as you cannot boil water if you keep putting it off the stove.
Steady practice also allows to create a habit of doing Magick, that is also very important for the change of perspective I have mentioned in article "Defeating theory, part III". Also if you practice isn't steady, you shouldn't consider that everyone has the same problems you do.
What I have noticed a lot in those who over-practice is they hate their practices. They hate doing the daily routine they chose for themselves. Your practice should be enjoyable, have fun. If your practice starts boring you, change it a bit, experiment with new things and always make sure to track it.
People also claim they do not have time for steady practice. Of course you do have time, a normal person sleeps for about 7 to 9 hours, that still gives us 17 to 15 hours of waking time. Not only that, but also a lot of practices can be integrated into the mundane life. For example in the "Sex and Magick" article I have mentioned a practice you can do every time you sit. Similarly you can take a 5 minutes of your lunch time for meditation. During lunch you can also practice conscious eating and drinking (mentioned in Magickal Curriculum). During boring meetings you can practice telekinesis on your cup of coffee. The point is that Magick should become the integral part of your life, not something you add to your already existing schedule.
Avoid unneeded reductionism
I have heard that a lot from quitters. "I don't need to do the death posture, just focusing on the sigil does the work for me". Or "I don't need to draw sigils, I will just focus on my wish and via Law of Attraction the universe manifest my desires". They also tend to argue with others about using "pointless" rituals. Later such person quits and says that Magick doesn't work. Well, are you sure Magick doesn't work when you never tried it?
I am not saying that modification and reduction aren't needed, I am chaote, after all. But this method of working should be done AFTER you already had some visible and verifiable results, AFTER you got your feet wet in the rivers of Magick. I have it hard to look at, when someone claims about how many things are not needed in Magick, not much because of them, but because of their readers. These people tend to find followers quite quickly. People who believe them and believe in their words. Imagine the betrayal when such a person, person viewed as the spark of light in the moments of darkness, turns out to be quitter and claims that Magick doesn't work.
To explain this a little better I will return to my original "boiling water" example. Normal and educated reductionism says you do not need to salt the water and you can still boil it. Or you can omit the lid of the pot and still boil the water, it will take longer time and more water will vaporize and get lost, but you will boil it. Uneducated and inexperienced point of view usually leads to "you don't need the pot or the stove to boil the water", so in one case a cold water will keep sitting in the pot doing nothing and in the other you will pour water right on the stove, effectively putting of the flame.
Keep an open mind
Belief is one of the most important aspects. The belief in success of your operation is vital for your Magick to work. And such a believe must be limitless. Now, I am not saying you should believe whatever you want and don't have any doubts at all. All I say is everything has its time. Don't be negative before and during the operation. But during the analysis of results be a little skeptical, it's actually needed to avoid the confirmation bias (the very same confirmation bias that reductionists suffer during their early stages).