How to Upgrade Your Base Efficiently in Clash of Clans

Decide what type of base you want. Several new "types" of bases are out there, the main two being a Trophy rush and Farming base. If you are trophy rushing, upgrading your barracks, army camps, laboratory would be the best for you. If you are farming, where you stay in a low league than you could be in in the effort to build up lots of materials, then upgrading walls, defenses, collectors, and storages is the way to go. Trophy bases protect the town hall above all and try to prevent their attacker from getting any stars. Farming bases often have a semi-exposed town hall to lure attackers looking for trophies and center their loot with the most protection. Hybrid bases try to protect both your town hall and your loot. They aren't the best at either but are a jack of all trades.

Max out collectors first. If you start to go for other things like walls and defenses first, it is going to take a long time to get the gold and elixir needed for these upgrades. If you have your collectors maxed out for your level, then you will be able to get these upgrades faster in the long run.

Go for walls and defenses. Put defenses as priority over walls, and the defenses you want to upgrade first are mortars and air defenses, as all attacks use a creature that can be taken down with one of these two defenses. Upgrading the walls to the max may not be efficient for your town hall, such as town hall 7 where the walls cost 200k gold apiece. Splash defenses like mortars and wizard towers should be prioritized. Save one builder inactive to spend extra gold on your walls. Otherwise, you will quickly fall behind on those.

Buy builders. Builders allow you to build more things at once, maxing out at 5 builders. These cost gems, but don't waste gems on speeding up production. Use them on buying builder's huts as they allow you to build things faster.

Have a good base layout. There's no point in trying to stock up on supplies if you lose all the gold you make in one attack. Keep your dark elixir drill and all storages in the very inner part of you base. Then surround them with your defenses to make people go through all your defenses before they can take your supplies.

Don't town hall rush. Some people only focus on upgrading their town hall to get the most defenses quickly without actually upgrading their defenses. Upgrade everything to near max before trying to upgrade your town hall. The exception to this is if you have all your elixir upgrades maxed, but still have defenses to upgrade. Then you should go to the next town hall so you don't waste elixir. This is the case for town hall 8 and once you run out of elixir upgrades, move to town hall 9.