If you are rhythmically challenged like me, NEVER practice without one.
Simple practice
Warm up with-
Scales with metronome, gradually increase speed
Chords with metronome-
If you are just starting try playing
AA AB AC AD AE AF AG, BA BB BC BD BE BF BG, CA CB CC CD CE CF CG, etc...
Play two old songs
Break
practice/break-down areas to work on/practice til perfect on two new songs
break
practice technics (tapping, alternate picking, finger picking, whatever you are working on presently)
break
play you 3 best songs.
drink beer and listen to the tape you made of your 3 best songs to find out how it really sounded and how well you stayed on the beat.