Fixing botched paint job?
Single stage paint is not intended to have clear coat. Do as in post 2
You can still use clearcoat with single stage paints, also. It won't hurt anything. Be sure to sand down what you have now so it's smooth first. If you're doing it in a wet-on-wet situation, just be sure to use the same compatible clear coat system. If the paint you have on it now is cured, then it should be sanded with 600 grit or finer before clear coating or proceeding to respraying.
In this guy's case, if it were me, I would sand the car down with 600 grit, then give it a fresh coat of the yellow using a base coat color which is more forgiving and faster drying. Just make sure you don't really soak it and eat into the prior single stage paint because that can cause some wrinkling/lifting. Take your time and spot in the bad areas.
follow up with clear coat for the most forgiving fix. 3 good coats of clear to allow enough buildup that could be sanded and buffed to a great shine.
or, you can use the single stage paint to spot it in and follow that with clear coats so that you sand and buff it afterwards. Again, make sure the clear coat brand is the same and compatible with you're single stage paint.
Hope that makes sense.
-that's this old body/paint guy's advice.