How do I hang wreaths on my doors?

Try command hooks.

I attach my door wreath to a ribbon and attach the ribbon to the top of the door with tape.

Would an over the door wreath hanger like this one work for you? https://amzn.to/2Sjixaj

If not, then I always use command hooks!

Put Command hooks on the inside of the doors. Use ribbon or fishing line to hang the wreaths and run it up and over to the inside of the door to the hooks.

suction cups works wonders

Command strips with hooks, of course.

I have used Command Hooks on both sides of my doors at one time or another. They easily go on and off without leaving any marks on my doors (both metal and wood). I have left the one on the outside of my front door year around without any trouble with the extreme heat or cold weather. I change my wreaths through the year for different holidays and some are pretty weighted. No matter what I hang I have never had one come down off the door or wall yet. I wouldn’t use anything else.

If you will always have a decoration of some kind how about cup hooks?

I have french doors and use suction cups.

Command hooks!

I would use the command hooks, but only put them on the glass. I haven't had luck on wood. They never hold up in the weather.

You can use a metal wreath holder or use Command hooks.