I don't recommend the use of outdoor car covers. They are no picnic.
Your car must be absolute clean before it goes on. If its dirty it will get on the inside of the cover and scratch/marr your paint.
Protect the paint with quality polishes/sealants/waxes. I use Klasse like many others.
What I would certainly recommend is the use of a soft top cover. which will keep it from getting dust int the fabric threads. It will keep the interior from fading and preserve your rear window.
The less you touch the paint of your car the longer it will last.