Practice basics using Master Itosu exercises. This format is great for many reasons. It teaches basics while using movement which is a valuable lesson itself. It is also similar to kata. If you memorize Master Itosu exercises as though they were a kata it will improve your ability to learn a kata and be a valuable tool in your martial arts life.
Practice your basics thinking of the bunkai. This will most likely involve a combination of your basics.
Change your stance/angle as you do techniques from basics.
Practice on a target. This does not have to be a professional punching bag. You could improvise something. One of the most brilliant improvised targets I've heard was a tennis ball hung by a string in a doorway.