I myself would use the clay bar. I love the way it leaves the finish so smooth. Anytime I wax my vehicle I use the clay bar first. It makes waxing so much easier and looks nicer when job is done.
This is how I would do it since this is probably the first time you have waxed this vehicle in a long time.
1. First wash vehicle with DAWN DISH SOAP (only use this when your going to clay bar your car because it strips all the wax from your paint and is gentle enough not to harm it).
2. Clay bar
3. Apply a good wax. Meguires is good. I prefer Zano but that is a brand not sold in stores. Mail order only.