1. Keep it short, but consistent
You’ll be far better off having fun, energized practice sessions for 15 minutes five days a week than doing the hour long marathon just before heading off to your lesson (hey, we’ve all been there). That said, if time starts to fly and you find yourself in the flow, go with it! Just pay attention to those mind and body signals that will let you know when it’s time to give it a rest.
2. Use a time keeper at least once
You don’t need (or want) to play everything using a metronome, however dedicating some portion of your practice to using a time keeper will yield untold benefits down the road. And if you’re working on a song, there are great tools that allow you to slow down an mp3 song to whatever tempo you need. My favorite is listed in the 5 Guitar Must-Have’s article. Playing along to a song is as effective as playing to a metronome; In fact, it’s probably the next best thing to playing with a group of live musicians!
3. Play the whole piece
When working on a song or any piece of music, it’s common (and important) to focus on the portions that are new, or areas that need work, so you can perfect them. But always dedicate some time to playing “the whole thing”. This could be the entire piece of music or simply all the elements you’ve learned so far. Focus on playing through without pausing between sections and regardless of any mistakes. This will help bring flow and continuity to your playing.