Originally Posted by abehanna
You need to strip everything and start over... I would recommend a good wash (use dawn or other dish soap to remove wax) and then clay bar, followed by a good polish with a DA and good pad if you can afford it. I use Meguiars 205 for light polishing or Meguiars 105 followed by 205 for heavy scratch removal / finishing polish. Then follow those with a good sealant (a good wax or even the nu finish will work fine).
After this point your paint will be clean and polished and with good washing technique you should be able to keep things looking good. Wax will need to be reapplied every month or two (other types of sealants can last longer Ive never used nu finish so im not sure how well this will work) and you can touch up before waxing with a good polish if you need to remove swirls or any other defects.
Claybar and start from zero.
I'm not a fan of Nu Finish. I'd highyl reccomend Meguaires products. Everything I've used from them works as advertised, and they have a nice line of Professional products if you need something heavier/really get into detailing.
Waxing is done after polish. Polish is removeing scratches/defects (paint correction), and waxes are used to protect (seal). It should always be polish before paint. Imagine it like sanding. Polish is 220, wax is 600.
Depending on the time between waxes and the condition of the paint, simply a new coat of wax could be sufficient a month or so if you please. Environmental effects (weather, road debris, etc.) will vary this number.
Wash (remove clay dirt/residue).
Meguaires ColorX (You might have to work it in. It's a polish that leaves a wax. It's a great one-stepper available anywhere)
Inspect (see if you want another coat. One might be good enough)
Meguaires NXT Wax (Technically a synthetic sealant since a wax is a natural product. It lasts longer, performs better, etc.)
For upkeep wash with soap (Meguiares Gold Class is great), and use some Meguaires ultimate spray wax. It's meant for plastics and can be used in the sun as well. Use once a week after a wash.