It's a lot easier when the car isn't your daily driver.. and you're not pinned to a time-sensitive deadline such as "I have to get to work tomorrow".. but I suppose sometimes that can help the "I've got to figure it out factor".
Ultimately it just takes getting in there and doing it. The simple installs like CAI and engine parts with good instructions are the easiest. The replacement stuff is usually covered by the Haynes as you mentioned.
99% of things you can get by with a decent 150pc starter kit from Sears. Nice part about Craftsman is the replacement factor if you break something trying something you probably shouldn't have with that tool or socket.
More often than not the tool adding is driven by necessity.. crap I don't have that tool.. time to jump in the (again.. hopefully not the only) car and run down there and pick it up.
Going out and getting a full toolset, especially from a higher end mfg like a snapon can break you right there, before even considering a tool chest to hold them in.
Just get in there and do it. And if you want the respect from the boards and have some extra time, go the extra step and document everything, so someone else later can benefit from your exploits, and learn from the things you did... there is almost NEVER a circumstance where once you've done an install you wouldn't do it significantly faster the second time knowing the tricks..
Not to long ago I did the same thing.. instead of just having our techs install some camber/toe arms, grabbed a couple guys from marketing and decided to knock it out on a Saturday in a driveway.. I now know a lot more about the Z33 suspension..
Rear Camber & Toe Arms Installation - G35 Coupe | STILLEN
Front Adjustable Upper Control Arm Installation - G35 Coupe | STILLEN