(1) Don't talk about haters, and/or playahs. Bitching about playahs is played out. There are people in life who won't wish you well, but that's their problem. Get over it. Got an ex who pisses you off? Join the club, that's why they're your ex. It doesn't make them a playah. Calling someone else a playah just means you are letting yourself get played.
(2) Don't talk about smoking weed: Grass, Weed, Trees, Tea, or whatever you want to call it. It's nothing special. 14 year old kids at the skate park smoke weed. It doesn't make you sound tough. It was a thing, many years ago, but it should be anymore. Give it a rest.
(3) Especially don't brag that you smoke impossible amounts of weed: pounds, tons, or a stone if you're British. Weed makes you mellow, in case you haven't noticed, not tough.
(4) Don't release every fart you make on SoundCloud: Not even your own Momma wants to hear all the stuff you're "releasing." Do us a favor and release the best stuff.
(5) Buy a good recording mic. A good mic is cheap, anywhere from $60-$500 for starters. Wanna spend more money, you can spend up to $20,000 rather easily, but one good mic can change everything.
(6) Master you mixes. Don't just put songs out, master them, if you don't know how to do it, learn to do it, or pay someone to do it. There are guys online that master well for $20-$30 a track. A little EQ, compression and limiting will make your song sound like a "real" track.
(7) Learn about music. Learn the notes on the keyboard, learn to play something. Be able to work on your own beats, or at least be ready to communicate with those who do. Know what a triplet is, a poly-rhythm, a tone, semitone, whole note, etc.
(8) Most importantly, don't be afraid to put in a rest once in a while. It's the blank spaces that give the beats in spaces power. There are times why you need to power through a verse, but not every time.
(9) Don't mention the year in a song. Yes, it sounded super cool when Chuck D did it in "Fight the Power," but other than that it makes your material sound dated. "Two thousand and twelve, all new baby," doesn't sound so cool in 2015.
(10) Lastly, but not least, don't be afraid to rap a light verse, have some fun, don't be so tough-nuts all the time.