- Free the Brotherhood Initiate
- Complete any previous quests that you haven't completed
Now that you have your hands on some good old power armor (Brotherhood for those without luck and repair), can complete many quests now.
Now, even with your power armor on or not, the first thing is to go to Old Town. There is a shack with some guards. Kill all of the guards with a shotgun or combat shotgun. Be prepared for a good fight: Ian and Tycho both need good arms. Before the fight, you can sell all of the leather armor, the metal armor, the Desert Eagles and their ammo, and the 10 mm pistols for some good weaponry.
For instance, I bought a combat shotgun for myself and a sniper rifle for Tycho with just the leather armor. I gave the SMG I got from Vault 15 to Ian. You can also sell your old shotgun for some ammo. To kill the guards, talk to one of them. You'll enter combat immediately.
Talk to the man in the green shirt (use the lockpicks). After you've picked the lock, speak with him and tell him that you're an Initiate. He'll thank you and leave. Save before going to the Brotherhood. It's a good idea to re-supply for ammunition and chemicals before you leave.