After that, stock the hell up on stimpacks, super stimpacks, doctor's bags, Psycho, and Med-X. Give Boone the best combat armor you can, along with the best melee weapons you can (he's a stone cold killer with a golf club and his sniper rifle). Next, I'd recommend getting Boone and the Eyebot as your companions. Ignore anything with low damage values, obviously. Then make your way out to the Brotherhood weapons dealer, and buy either a fantastic plasma weapon or their marksman carbine. This armor is at full strength, and has fantastic protection value. Make sure no one is around, sneak, and steal the armor (and the weapon, if you want). In his room should be a full suit of power armor, a plasma rifle, and assorted goodies. When you can use power armor, go into Hardin's room right next to the main Brotherhood of Steel leader's office.

The second is access to their weapon dealer's full inventory, which has some ridiculously awesome weapons. Eventually, you will have the option to join the Brotherhood of Steel, which is a smart move because it nets you two awesome benefits. If you haven't already done so, do the Brotherhood of Steel missions. Slight SPOILERS ahead, but nothing major. It's going to be time-consuming, but it'll benefit you greatly in the long run in other ways, so keep that in mind. Here was my solution, since I hate sneaking past them all.