Every pitcher has one problem in common; sometimes you need or want to practice your pitching and can't come up with anyone to catch for you. Worry not! You don't need a catcher, a coach or even a softball park to practice your pitching.
First Things First
Find a solid concrete or foundation brick wall; a handball court wall is ideal. Take a piece of chalk and draw a strike zone box on the wall. Make it the strike zone for your height. Then draw a line through the box, going from left to right, at the same height as the belt on your waist. Draw it all the way across the strike zone box you chalked out. Measure off the same distance you use at your level of play, from the pitcher's rubber to home plate, and then subtract two feet. You want the distance to be where the ball may or would be hit by the batter, about 1 foot in front of the plate. Throw from there.
Location
Work on accuracy first. You should be able to catch the returning ball without stepping left or right. An accurate throw will return straight back to you. Once you have become consistent at doing that, then work on throwing harder. Remember, to give up a handful of accuracy for a pinch more speed, is NEVER a good trade. Accuracy first, then work on speed.
Velocity
You don't need a pitching coach, or an expensive radar gun, to tell you if you are throwing harder than you were a few weeks ago. The harder you throw, the closer the ball will return to you without hitting the ground. If you can catch the ball without it hitting the ground, or without you taking a step closer to the wall, you have fairly good speed for your level of play. As you progress, when you catch the ball it will have more force behind it and you will be able to tell when you are throwing harder and faster.
Getting Into a Routine
Again, don't trade accuracy for speed. An 80mph pitch is not very impressive if you can't throw it for a strike. When you do the wall workout, take a portable radio/tape/CD unit along and play your favorite lively paced music. Try not to play slow stuff because that tends to slow down your workout pace. When I was a kid I threw for an hour a day after school.
Don't use "I couldn't find a catcher" as an excuse not to workout your pitching arm. You don't need a catcher, a coach or a radar gun to workout and tell you if you're throwing faster. We'll just keep that between you, me and the wall.