First off, that beat is epic! Simple and super catchy. And your lyrics go well with it and you have very good timing in your rapping. You should:
Put an eq on every channel except the Kick and high pass filter it to 100 hz. Vocals & snare a little lower, like 80-90 hz. This lets your kick drum come through instead of being masked by everything else.
Denoise your vocals using whatever program you use, followed by the high pass filter mentioned above, then compress the vocals. Try "parallel compression" on your vocals using something easy like
Download Free Leveling amplifier plug-in: TLs-3127 by TbT.
Parallel compression doesn't take forever to learn and it sounds awesome. Most bang for the buck. You will have to watch a quick tutorial or something on how to parallel compress though, I don't want to write 5 paragraphs on it when u can watch a quick video lol.
And I'd be wary about mastering. It requires a specially trained ear and a multi-thousand dollar room to do correctly. Get it mastered online for cheap instead.
BUT what you CAN do is put a compressor on the master track and compress your whole song by 1-3 dB. It's called "mix glue" and helps your whole song feel more cohesive.
Hope that helps! Great music overall!