Here are the steps you can take to improve your weaker leg kicking:
1. Stretch the weak leg muscles well before kicking to warm-up and prevent possible injuries.
2. Strengthen your weaker leg by doing very slow controlled kicks wearing a light (2 to 5 pound) ankle weight. Start with the lightest weight and work your way up.
3. When practicing kicking in the air, choose a specific target before you kick. Do 10 to 15 repetitions of each kick with your weak leg whenever your practice to improve your flexibility and control.
4. Practice 3 sets of each kick on a heavy bag or handheld target at each practice session to develop power.
5. Work on the above four suggestions consistently, at least 3 times per week. You should begin to see results in a few weeks.
6. Set specific goals (like you want to do a front kick at head height) and track your progress in your training diary or notebook.
7. Every two weeks re-evaluate your progress and goals using your training notes and your observations.
Sang H. Kim