Some of them do work and some of them do not
Keep realizing what the differences between 'reality' and 'fantasy' are.
Learn what we can achieve by developing our spirituality and working with energies. We can psychic defense, achieve emotional states and affect feelings (which are associated with energy, thus they are spiritual), get a positive / negative attitude, or simply direct energies (feelings as well) upon a specific desire / intent.
What we can't achieve is a physical change, since things that belong to the spiritual field will always belong to it. Things that belong to the physical field will always belong to it as well. Physical changes talks about transformation, physical changes (appearance), etc.
Here's a nice categorizing of the spells to two groups which might be useful for your question:
Real magic spells - These are real magic spells that actually work for the magic practitioner if he/she casts it properly. Such spells will work for you if you know what you are doing, if you are experienced and familiar with the basics, and work better if you will choose to follow some optional traditions like : colors, planetary days and hours, moon phases, ritual tools and supplies, etc. Such spells always worked for me if they were casted properly, since they are magic spells that have potentially l to work,. Do not forget that this is about potential, and such spells really have it. By saying real magic spells i mean that these are magic spells that can be cast by magic practitioners. Such spells do not include physical changes and DNA changes, or any actual kind of transformation. This is the other sort of spells i am going to talk about.
Fluffy / fantasy spells - Such spells are not real magic spells. The magic practitioner will not be able to get results from them even if he dedicates as much energy as he can, and even if he / she follows all of the traditions and optional things. It means that they have no potential to work. No matter what the magic practitioner tries to do, and how. Such spells include : transformation, DNA changes, and other kind of things which can be found only in science fiction movies. You are able to avoid such spells by : personal experience, logic sense and maturity.
Use your logic, maturity and personal experience with the craft and you're fine.
I hope it helps !