Replying to Tips for Rap recording / what effects to use (autotune??)

i have recorded about 400 freestyles, and just started making actual songs, and would any tips from anyone who knows shit about making it sound professional

I am using Garageband, and the mic on my macbook pro, i have a real studio mic, but dont know how to hook it to my computer (its MIDI, idk how to USB-ize it)

Should i use autotune on the verses? Just Chorus, none?
What effects can i use to make my voice sound like... smoother.. more prooooo

any resources/advice is appreciated yo

working on this now, doesn't sound professional enough though,

http://www.mediafire.com/file/muwnzzjjncm/I Love High School PREVIEW.mp3

(note there is some autotune on my voice on this, but not in the intro)