Kicking is mostly about balance and flexibility. So, it’s not so much about developing your muscles for strength, it’s about developing them in the right way. This one’s pretty simple because developing flexibility for kicks is all about making sure you’re including stretches for the right muscles in your warm up regimen. Here are some useful stretches that will help you.
Remember, developing flexibility takes time and patience. Also, make sure you stretch before and after you exercise to get the best benefits. These are all stretches that develop and widen the muscles in the hips
Side Splits/Center Splits: this one is a little advanced so be careful with it and don’t push too hard, too fast because this can injure your legs if you go too hard in the beginning
Front Splits: Same rules for caution apply to the front splits as it does for it’s cousin
The Butterfly Stretch: simple and safe, but take it slow and don’t push too hard
Work your core:
These are all good, but it’s going to take a few months and even a few years before you start to see significant improvement. Be patient with your body and consult your instructor if you have questions. They may also have good tips. (I pick flexibility over specific muscle strength because flexibility is what governs the speed that makes a kick successful.)