Do breathing exercises on a daily basis. One of the best exercises to do to make your falsetto stronger is to lay flat on your back with your hands around your waist and your index fingers pointed toward the center of your stomach. Breathe in slowly until you feel your stomach and hands raise up from the added air and then breathe out slowly over 15 seconds. Doing this exercise 10 to 15 times in the morning and before bed will greatly help you control the rate in which you expel air while singing. This is important in all singing, but particularly important when using your falsetto.
Practice your vocal scales at the piano or keyboard everyday. While it may seem a bit tedious to sing scales over and over, it is an essential part of learning notes and their relationships with one another. To practice your falsetto, start at middle C and work your way toward the treble side of the keyboard. It is important that you push your voice a bit when learning to use your falsetto, but do not overdo it. Singing should never hurt or cause you to get a sore throat. Different singers have different natural ranges, and learning to sing higher will take practice.
Set a practice schedule for yourself. Practice singing about an hour every day unless your goal is to become a professional singer or you are rehearsing for a performance. Always warm up with your scales before moving to singing more complex songs. If you need to rehearse more than three hours per day, it is important to take frequent breaks and drink plenty of water. When practicing your falsetto for a long time, it is important to make sure that you work on your chest voice as well, your lowest, deepest singing range often associated with bass sounds and the opposite of your falsetto voice, as you will need to be able to move from your chest voice to your falsetto regularly.
Record yourself as you practice your falsetto voice. You don't need fancy recording equipment to record yourself practicing your scales or singing along to an accompanist. A simple hand-held tape recorder or video camera will allow you to listen back to your practices so you know which notes and areas you are having the most trouble with.