Building a base is quite a challenge in Zombs.io. You will need to make sure that it looks decent, and most importantly, survive the endless zombie waves. After playing zombs for some time, I've come out with this new base idea (maybe someone already done this before, but meh.)
So basically, to build this base, you must get at least 500 wood and stone. To do this, just simply go to a place where a tree and a stone deposit spawn right next to each other, and grind. Make sure that you get 1 wood and 1 stone for each swing. If you want to skip the long progress, just hold left click, and press ctrl+ tab/ ctrl+ shift+ tab to switch tabs. Go back to the zombs.io tab, and you will find yourself grinding automatically. This is a common exploit in many other io games, and it's not illegal at all, just a bug or something. With this bug exploit, you can afk and let your character grind until you think it's time to build a base.
Search for corners, and put your gold stash at the furthest edge you can find. I recommend doing this in servers with less players, as the corners may be already occupied in huge population servers. Surround your gold stash with gold mines, then bomb towers, then arrow towers, then cannon towers, and finally, mage towers. Bomb towers have a larger range, so they can be placed behind. While mage towers have a smaller range, so they may as well go to the front. Protect the towers with walls, slow traps and doors, and you can as well use melee towers behind walls (they can hit targets behind walls). Place resource harvesters at the sweet spot where a tree and a stone spawned together. Wait till night, and see your base in action!
If you used the base layout in the image above, you will notice that the zombies will spawn in only two sides and will avoid the places full of walls. Your towers will have a lot of time to hit them while they path find, and won't be overpowered by the zombie waves. Congrats! Now all you had to do is upgrade this sweet sweet base, and enjoy this sweet, sweet game!