Get the Railroad Rifle asap. Probably the coolest gun in the game, and most satisfying. When you shoot it in vats it makes the sound of a locomotor train and can pin body parts (namely heads) to walls, roofs and floors.
Get the repair skill to 90 quickly. This means that all of the weapons you ever pick up, if you keep them in good condition, will last AGES and do far more damage than ordinarily possible.
Collect bobbleheads. They make you happy.
If you have Broken Steel installed, find Dogmeat and keep him with you at all times. No shit, he is actually invincible if the expansion is installed, and he's pretty damn useful for finding meds (that is if you like your meds to be beer. ALOT.). I actually tried shooting him directly with the MERV Fat Man and when I went to check on him, vats said he'd only lost 1 bar of health! Dogmeat will save your life.
Don't bother carrying radiation-suits. You'll find so many 'radaway's and Rad-x that there really is no need, and it takes a very long time to develop anything serious from rads anyway. Infact if you did the Wasteland survival guide fully, rads can be a very useful thing if you overdose. I'll say no more than that.
Get a house. Hoarding unique items and "pieces-of-junk-that-I'll-make-things-with-sometime-but-never-actually-do" is fun. Just don't stack it all infront of the doorway, otherwise your robot could send it all flying and actually kill you (no joke it happened once).
And finally!
If you get Colonal Autumn's Uniform, Poplar's Hood and a Deathclaw Gauntlet, not only will you be the most agile, stealthy and downright dangerous melee character ever, you will also look just like Alex Mercer from Prototype. Try it out, you'll thank me. = )