to get the bad stuff out there's this...
http://autogeek.net/medicutco85.html

for medium stuff there's this...
http://autogeek.net/memecutcl1.html

for final polish to really bling it out, there's this...
http://autogeek.net/mg03.html

and to make sure you're not adding to the swirls and scratches make sure you only use clean microfiber towels to wash, dry, and wipe up after polishing. use normal towels, even 100% cotton ones, and you'll just scratch it up again. only using microfiber stuff will keep you from scratching it up again after all your hard work polishing it.

 

Even easier if you go to autozone or an auto parts store you can get a few things to get them out. Clay bar first of all if its just deposits on the paint. Second thing would be a orbital buffer with a terry cloth bonnet and the meguiars 3 step system (I only use step 1). All you do is apply the paint cleaner to the car and use the buffer to move it around. It should remove the water spots just fine. For light scratches you can use scratch x or use the 2nd item in the 3 step process. Then follow it up with a wax. Wax doesnt really take out marks on the paint, since its not an abrasive.

Make sure before you clay bar or buff the paint you have washed the car. Even if you drove it to the store and back, wash it again. The key is a clean car, if your car has dirt on it you are only going to make the paint worse.

If you have swirl marks in the paint (looks like a haze or real small scratches in circles) that means someone buffed it with a buffer and didnt do it right. Those can be taken out with a foam bonnet and some scatch x or 3m swirl mark remover.