Reply to Mastering Questions

Yo yo,
Ableton Live.
Looking to master my tracks. A dad's friend of mine works on production but for kid television shows. He claims he can master a track for me. Any reason not to? Free + Easy? Other options?
Also,
What state does the track need to be in to be sent to mastering? Frequency wise? Each sound + hit is Eq'd.
How much of a difference does mastering a dubstep track make?
Sorry for the question rampage.
J