How can I prevent a metal front door paint from peeling and chipping?

it is all in the preparation, most new doors come primed only. If yours is already painted, sand it down to get a rougher surface for your paint to stick, wipe it off with a damp cloth, then prime the door and paint with your colour choice, can be rolled or sprayed. If you have the budget, take it to an autobody shop and ask them to paint it. (Autobody paint is expensive though). Fortunately, I had a friend in the trade, so when I saw him doing a job in the colour I wanted I asked if he could do my door at the same time. This was less costly for me.

Prime it with Rustoleum metal primer, and then paint with their marine epoxy.

Sand lightly and then prime with Zinsser Bullseye 1-2-3 primer and then put on your finish coats, preferably 2.

We live in Phoenix, AZ... our front door faces directly west... so it literally bakes in the afternoons, especially in the summer... when we painted the house I used Exterior latex paint on the door and shutters... and now the paint on the door is cracking and peeling.... as soon as the weather cools off in the fall i am going to use a heat gun and remove the paint from the front door and sand it down.... then I am going to prime it and paint it with a HIGH Heat paint... like for barbecues or car engines (more colors).... hopefully the high heat paint will last better than the house paint did.

sand, prime with exterior metal primer, allow to dry and use a exterior metal paint

Thank you