What do you do to avoid jealousy?

Love dissolves jealousy. Learning to love yourself more is more self respect, more self appreciation, more self acceptance, more self approval.

You can look yourself in the eye in the mirror and say "I am willing to change, I am willing to love myself more, I deserve to be happy just because I exist, I forgive the people who taught me to be jealous an set myself free, I am at peace"

You could repeat this hundreds of times.

Jealousy isn't really a bad thing. It's natural.

As long as you don't let it get out of control, you'll be okay.

And in order to keep it in check, be sure to express how you feel, respectfully.

Of course, like All in the Mind said, you have to learn to trust yourself and others as well.