you have been given good, and to begin with, inexpensive advice. Start cheap and easy. Start here:
Beyond that, there is no single answer that fixes every single a/c issue that could possibly happen, except for: Replace everything. Compressor, clutch, evaporator, condenser, drier/accumulator, sensors, hoses, controls, electrics, blower, piping, blend doors, etc, etc, etc.
If you didn’t like the answer one shop gave you, find another and get a second opinion and compare.
but, as has been said, if you continue to try to repair yourself and don’t know what you are doing, you could seriously endanger yourself. Never mind, the legal ramifications of your community in regards to releasing refrigerant into the atmosphere.
good luck, and please be careful.