My mom does this, and my best friend does it as well. I intend to do it once I fully relax in august.
The main thing to remember is:
Get hair that blends
Get a good cut to blend your hair into the extensions (this can be done by adding layers, or getting a razor comb and slicing into the extension hair right where your real hair ends)
Take care of your hair in between the tracks
Get them tightened up when it becomes loose
Stay on top of your treatments and trims