If you're gonna do it yourself realize that 98% of the common wisdom is urban legend + marketing hyperbole, rather than the boring science of getting something clean without damaging it.
Basically you don't need more than ~$50 of stuff to have your car look better than 99% of people who spend thousands;
if you use the right technique.
Here's your
basic starter kit and a
similar one and
one with a bit more detail, but more rambling.
In short, you don't need expensive pressure washers or foam cannons - those are purely for fun & add zero value ... but they are FUN!
- Do a nice wash w/ good technique
- Do a good panel wipe with IPA (50% isopropyl alcohol, 50% de-ionized water)
- Put on a cheap but decent sealant
- Wash your car every 3 weeks or sooner (prevents "contamination")
- put on more protection every 3ish washes
Functionally this is the exact same as $3,000 of professionally applied ceramic coating.
Technique trumps product by a mile.