Dash, polish is all well and good, and I can recommend Autoglym Super Resin Polish. It has a mild cutting action, and contains fillers so the micro-scratches and swirling you see should appear to be reduced. Basically, it won't get rid of them, but it will mask them pretty effectively. Once you've done the hard work of getting the paintwork to shine, the main thing is keeping it shiny, and without getting into what those crazies do on the detailing world forum,
do use the two bucket method.
This means when you wash your car, use two buckets
Dip into bucket 1 with the shampoo: dip your lambswool wash mitt in, wash the section of car.
Rinse wash mitt in bucket 2 which is full of clean water.
Repeat.
It doesn't add much time to the wash, and you'll see a load of grit and sand at the bottom of bucket 2 at the end of it. This is the stuff you would otherwise be working into the paint if you only use one bucket.
It makes sense, and until I saw what it was about on detailing world, I only used one bucket and a sponge. Using a lambswool wash mitt may sound extravagant, but it really pays off by keeping dirt and grit deep down in the pile as opposed to on the surface of a sponge. You can even hear the grit and dirt scratching the paint if you use a sponge. Not so when you use a deep-pile wash-mitt.
What I did last year before winter was:
Wash with the 2 bucket method.
Clay the car. I was a claying virgin, and as long as you use a lot of lubricant, it's really no big deal
I used cheap car shampoo mixed 1:1 with water and just let the clay glide over the bodywork. It didn't seem to pick-up much dirt, but the paint was totally smooth afterwards.
Wash again with the 2 buckets
Polish
Wax
For the wax, I used Collinite 476. After reading reviews of its durability, I can say that I'm extremely impressed. I'm certainly not a fan of spending an afternoon rubbing polish into large bits of metal, but the finish is great now, so I don't see myself having to do it again in a very long while.
BTW, I used this guy:
cleanyourcar.co.uk for all the washing supplies. He's priced very competitively and everything arrives well packed and usually next-day.