Just set your entire indoors as a burrow. It takes like 10 seconds once you know how. If you close yourself off from the outside somehow, you can even turn the alert off once everyone is inside. Every once in a while someone will do something stupid, but I honestly see that as a feature more than a bug. Otherwise it works near flawlessly.
Military takes a lot more in-depth explanation just due to the amount of micromanagement, but it works great.
Assign a commander and then a captain for as many squads as you want via nobles screen. Then press m for military, c to form squads, scroll with arrow keys and enter to assign dwarves. When the uniform option pops up, I just pick metal, which gets everything right except for a couple specifics I usually change (replace any melee/shield with crossbow/metal buckler for a ranged squad, replace metal armor with metal chain shirt/breastplate). They then equip themselves fairly intelligently.
Then the most difficult thing is scheduling, which you don't even need to get too in-depth with if you don't want. I can't remember the keys off the top of my head, but just set them to train a few months out of the year and make sure the minimum staff assigned to the task is less than the size of the squad or your soldiers won't rest when they need to. You can schedule them meticulously to the point that they'll handle defenses almost completely on their own, but it's just as easy to hit s, choose a squad, m, then select a spot. That squad will then move to that spot and guard it, killing anything they meet on the way or comes near that spot. When the threat is over, s, select squad, o, and they'll go back to whatever they were doing.