If you've never casted a spell before and you would like to, I think you should start with the basics a bit more. Meditation and visualization is a great start and so is astral projection, but in this case, I think you need to focus on visualization and intent greatly.
-If you want to do extremely well on a exam, you can find a spell or attempt to create your own that will influence your success, but please make sure you do put hard work into it by study and do not solely rely on the spell itself.
-For this, you could find or create your own luck spell, or a money spell that involves liberation of debt/fines. However, I think you should be careful and let your parents deal with this, because all spells can backfire and you don't want to make it worse that it already is.
Keep researching the basics and perform them at your own pace, and find spells/make your own that will be easiest for you to do as a beginner.