At the very minimum, you need...
*A good Car Wash shampoo. (There are many good ones. I like Meguiar's NXT or Duragloss #901)
*Two buckets. (I prefer 5 gallons bckets.)
*A good wash mitt. (Sheepskin preferably. I use and like the one fron Wal-Mart.)
*A good wax/sealant. (Generally, Sealants last while waxes provide a better shine. A lot of people prefer a sealant base with a pure carnuba wax topper. I really like Duragloss #601 +#105 topped with Duragloss #951 Aqua Wax once every couple of months. However, there are hundreds of combinations or single waxes/sealants.)
*Trim Shine/Protectant. (Again, there are many. I love Duragloss 271.)
*Tire Shine/Protectant. (Again, many. I use whatever is cheap at the moment.)
*Window Cleaner. (Stoners Invisible Glass is a good one.)
*Interior Quick Cleaner (Meguiar's Quick Interior Detailer is perfect.)
*Interior Protectant (A lot of people prefer 303 Aerospace protectant. Leaves a great natural shine.)
*Microfiber towels. (Can be found in many places.)
If you have leather, get a good cleaner and conditioner.
If is easier to keep something clean than it is to have to go back and detail it. Costs less too.
There are millions of good products. This site has many of them. If you search the forum and do some research before you buy, you will save money and be really happy with the products you purchase and you will be happy with the way your car looks.
**I don't work for Duragloss either.lol I have a local CarQuest that sells it for cheap and the more I use their products, the more they impress me.