This practice tip may sound ridiculous, but it will help your playing right away.
When working on a new piece of music or technique, it’s really common to move on to something else before the project is truly mastered. To bring it to a new level – play it for someone else. In fact, play it for anyone you can get to sit still for a few minutes: parents, siblings, the kids you babysit, your best friend, your spouse, a colleague, a neighbor, your favorite clergy member, your worst enemy, ANYONE. When you play in front of another person, you will quickly realize what still needs work, what can go wrong, and what sounds fabulous. It can be a great source of motivation (no one wants to play badly in front of anyone!) and can go a long way toward building your confidence.
Make playing in front of people a regular part of your practice routine (even force someone to listen to scales, if that’s what you are working on!) and see how ridiculously prepared you will be for your next big gig!