If you just want to wash it, I'd suggest buying the following basics below - the links are just examples of decent stuff I found in 2 minutes, not "must haves". You will get 20 suggestions for each one of these items if you ask, as it is a very personal thing.
2x decent sized buckets (one for your soapy water and one for rinsing your mitt) like these or bigger
http://www.polishedbliss.co.uk/acatalog/pb-clear-wash-bucket-cat3.html
1x wash mitt
http://www.polishedbliss.co.uk/acatalog/gyeon-q2m-smoothie-cat3.html
A decent dedicated car shampoo
http://www.cleanyourcar.co.uk/washing-and-drying/car-wash-shampoos/meguiars-gold-class-shampoo/prod_109.html
A decent, soft drying towel
http://www.polishedbliss.co.uk/acatalog/pb-luxury-drying-towel-cat5.html
If you're going mad, also get some wheel woollies for getting in the wheels
http://www.polishedbliss.co.uk/acatalog/pb-luxury-spoke-back-woolie-cat4.html
Also a third bucket and use it for the wheels only and perhaps even a dedicated wheel cleaner.
Get that lot and you're well on your way to clean paint and doing minimal damage during your wash.
If you've not got a pressure washer, suggest a sensible starting process might be:
Rinse the car off with a hose, shifting any loose dirt
Chuck the wash mitt in one bucket and fill with soapy water
Fill the other bucket with just water
Wash one panel at a time with the soapy mitt
Rinse the mitt in your rinse bucket after each panel
Soak the mitt in the soapy water bucket
Repeat this cycle until every panel and the glass is done - rinsing the mitt after each section.
Do, start at the top of the car and work down.
Do, rinse the whole car with an open ended hose when you're done washing.
Do, dry with your drying towel - not the sunshine
Do, the whole thing out of direct sunlight if you can. This avoids it drying too quickly and leaving water spots.
If you must do it in the sun, keep rinsing the car as you go round and keep it wet. If you let water and or soap suds dry on the paint, you're just making your own life harder!
Your basic wash is now done, but if you go for the wheel woollies, do the wheels first or last, but seperate to your paint.
NEVER mix anything that goes on your wheels with anything that goes on your paint, hence the separate wheel bucket and woollies above.
NEVER put your paint washmitt in the wheel bucket or on your wheels, the dirt on wheels is metallic and will scratch your paint for fun.
Enjoy