Make sure you have a quiet place where you won't be interrupted. I always practice in my den in the basement. Unless you have someone to quickly intercept phone calls or non-ringing voice mail, consider taking the phone off the hook for about a half an hour. Turn off the radio or TV.
Do a quick warm up, a scale or something you know for a couple of minutes. Then start with something difficult like the new song you are learning. When I'm learning a new song, I play it over & over for almost the entire session. The length of the session varies. I'm 45 now but I remember when I first started playing 31 years ago, I thought nothing of practicing 2 or 3 hours at a time. I'm lucky now if I do an hour. If you feel your practices are too tedious, practice different songs each day.
Finish up the session playing the most polished song you have with satisfaction.
Preparing for a performance is a little different. Play your songs completely through in the order you will perform them. If you use a capo or different tunings, arrange the songs so there is as little interruption between songs as possible. Think about what you are going to say between the songs. This may sound pessimistic but if you have an incredibly fancy move that you like to do during practice and you're not 100% sure of it, then don't do it during the performance. At best you're at about 80% efficiency when nervous and performing. You probably won't pull it off.
Bob, Gman ( o )==#