As you get further in the game, the buildings in your base will start to cost a lot more. Beginning with town hall six, they may cost more than 500,000 gold or elixir each. Because of this, you will want to upgrade your resource buildings as quickly as possible so you can gain more loot quickly. Next to should be your defense buildings. It is important to save up as much elixir and cold as you can. Before you log off the game, use all your resources so no one will still them. Find the troops that do not require much elixir in your army camps and train them.
Upgrade your collectors and minds first. As you upgrade your buildings, more loot can be collected each time. Do not worry about upgrading your vaults yet. Otherwise you will have to much loot. After your most expensive buildings have been upgraded, you can then level up your vaults. If you have extra loot, upgrade your walls are reset your defenses and traps until you have used it up.
Next, upgrade your small defenses. Your cannons and archer towers should be leveled up first since they are low damage defenses and are easy to upgrade. If you upgrade all your archer towers at one time, and then your cannons, this will benefit you by helping your defenses against both flying and ground troops. Also consider upgrading your traps and bombs as they are inexpensive.
Once the smaller defenses have been upgraded, start upgrading your bigger defenses. Clan wars and rating will help you to bring in the loot you need for the bigger defenses. These bigger defenses, such as Inferno towers, X-bows, and others cost a lot for upgrading. Try to save your clan war bonus and treasury bonus for when it is necessary.
Once the defenses have been taken care of, began working on your office of buildings. Your Clan Castle should be upgraded first. You will need to use your village guards to help protect any loot you have and to continue attacking so you can add more gold. You will also want to upgrade your army camps so you can have more troops for attacking.
Once these are done, upgrade any extra buildings such as your spell factory in laboratory. To have the strongest base you can, you will need to level up your buildings to their maximum level.