In all seriousness, don't buy any of those things until/unless you actually know you need it.
--Tuners: for many people a pedal makes more sense, because it can be used as a mute switch. Only get a rack tuner if you like having a big flashing-light display in your rack.
--Power conditioners: you'll want to search on "conditioner" in the Amps forum, for a lot of good and controversial reading. Also check out my blog for a post on this subject. The short version is that you're better off getting an inexpensive power strip and an outlet tester.
--EQ's: Generally the EQ on an amp is adequate; only get an external EQ if you know for a fact that the EQ on your amp is inadequate.
--Compressors: check the FAQ linked in my sig. A comp is a useful tool, but not necessary for everybody.
--Sonic maximizers: waste of money IMO.
The very first thing you should invest in is a large and well-designed speaker cabinet that can take plenty of abuse and sounds huge. The second thing to invest in is a really good and powerful amp head. After you have those dialed in, if there is still any function or tone lacking, you can analyze exactly what is lacking, and buy the appropriate piece of equipment to fill that need. If you need more compression functionality, get a compressor. If the amp EQ is minimal, get an EQ. Etc. But do not imagine that any of those accessories will be inherently useful to everyone, or worth your hard-earned money.