and yes, I did benefit from it a lot! I warmly recommend it. Try it, it worked great with me
Here some advice based on my personal experience :
The biggest difficulty is to find the right affirmation. It has to be as precise and concrete as possible. (for example not " I am angry because people never listen to me" but "I am angry because on 13.march this year, my friend X did not listen to me." ) And carefully worded. Use words you would really use, not a "light" version of your problem. For example, do not say "I am angry because this guy called me a jerk" if you are in fact thinking "I'm so damn f****** angry cos this a**h*** of a son of a b**** called me a f****** jerk!" Use the second sentence then
If you cannot clearly define the problem, begin with an emotional feeling or a physical sensation you have about it. (for example with the pressure on your stomach or the feeling to be lost) That will clarify your thoughts a lot and eventually lead to a precise definition of the problem (maybe in many steps). And don't forget to love yourself in your affirmation while you're touching the first point on your chest : "Even if <problem>, I love myself unconditionally and always stand by myself" (or some other nice things about yourself).
That's all, enjoy!