People that are too nice usually are not 100% confident and ask for approvals from others.
It's nothing wrong in being nice, but being too nice to someone that didn't deserve it yet is wrong way to go. Woman usually take advantage over "too nice guys". The best way to get over it is to LEAD, be the alpha men. You can be nice, but dont take their bullshits. That's the difference between confidence nice guy and AFC nice guy
.And its nothing wrong in being cocky or teasing girls. Indeed, you must tease them. I always show sexual energy with my teasing jokes. Try it every day on other girls and with time it will become natural to you.