I use multiple gates and layers of walls and spikes at my main entrance and at my bridge. Then build walkways above to rain down death on anything hitting the first layer. I also have covered fires within range of the area so that raids during storms are less painful because at least the cold debuff is removed.

That way if I ever start using the cart in earnest I have a way to get it in the base.

I've had trolls attack the gates a couple of times and they can cause some serious damage so I prioritize those raids quickly. Since they are coming at one location its pretty easy - especially if you use copper arrows.

The first post is equally effective though. Its just a little more boring to me and I wanted to use the games fortifications to see how effective they are.