Well here are a few tips (this probably should be in help though)
1. Build your weakest walls on the outside. Due to splash once a strong wall is broken it will destroy weaker walls behind it. So put stone hedge on the outside, then directly behind it plank, then brick.
2. If you want to build multiple layers of the same wall make sure there are 4 tiles (I think) between one layer and another so that splash won't hit it.
3. use Alt + R (if you're using a custom client) to make sure that all of your walls are covered by braziers. Also if you have the resources make them a "turret" where you build a little stone wall around it with a gate. That way once they breach your outer wall they have to break another layer of stone wall for every brazier they want to break.
4. Build another layer with braziers inside of it around your claim stone/town bell. Make this the best wall of you have and if possible make it so that the braziers that are turreted can also hit those attempting to break into your "vault" this is also where you can store your best stuff.
5. Torch post coverage is practically free, they don't do a ton of damage but every little bit will help and they can score crits. So may as well make sure your wall has full torch post coverage also.
Here is a picture (I made in about 5 minutes) of a base that kind of demonstrates what I'm talking about. The spacing ect. is all wrong but it kind of gives the idea. The gray is a stone wall, the black is a brazier with a stone wall/gate around it, brown is plank fence (a brick wall would just be the exact same stuff). It'd be up to you if you'd want to put brazier coverage on your outer most wall.
There's a couple other things I'm probably forgetting to point out, but that's kind of the gist of it (oh and don't forget to lock your gates.
