I just broke 100k, even if barely. just starting to get a grip of the game mechanics. the general strategy I've found is:
1. jump kick. this cannot be stressed enough. you're basically invincible while you do this, however dont just jump and kick immediatly, but rather jump then time the kick while midair, else your kick will end too soon and you risk missing the enemy.
2. to defeat bosses, jump kick => run back => face enemy => jump kick. as long as you keep the right distance the bosses tend to jump at you while you jump. just kick them while midair, then run back as soon as you hit the ground. the only problem is the other enemies on the screen being in your way, if they are then just jump kick back instead of run back and just hope you don't land on any enemies.
3. on the third stage, the place to be is on the arch. the boss has to jump up, giving you time to be prepare. kick him to send him flying down, and wait for him to get back up. also the enemies cant jump up in the middle of the arch, therefor it's a somewhat safe zone to stand.
4. the morningstar-looking thing can be reversed as the other guy said... it's quite useful against bosses, especially when they have other enemies around them.
EDIT: hey, it didnt submit my score! I just got 133.900 but it wont upload it! says the server isnt availible :/