Upgrade priorities at Town Hall 7 varies slightly depending on your focus on war or farming.

War focused upgrade path
War FocusFarming Focus
Tier 1Build Dark Elixir Storage.
Build Barbarian King.
Build Dark Elixir Drill.
Build new Army Camp.
Build new Barracks.
Build Dark Barracks.
Build Dark Elixir Storage.
Build Barbarian King.
Build Dark Elixir Drill.
Build new Army Camp.
Tier 2Laboratory to level 5.
Spell Factory to level 3.
New Army Camp to level 6.
Barracks to level 9.
Dark Elixir Storage to level 2.
Barbarian King to level 5.
Dark Barracks to level 2.
Build all new traps, defenses, buildings and walls.
Tier 3Dark Elixir Drill to level 3.
Elixir and Gold Storages to level 11.
Elixir Collectors and Gold Mines to level 11.
Laboratory to level 5.
New Army Camp to level 6.
Spell Factory to level 3.
Dark Elixir Storage to level 2.
Barbarian King to level 5.
Tier 4Build all new remaning traps, defenses and walls.
Get them on par with Town Hall 6.
Dark Elixir Drill to level 3.
Elixir and Gold Storages to level 11.
Elixir Collectors and Gold Mines to level 11.
Barracks to level 9.
Dark Barracks to level 2.
Tier 5Air Defenses to level 5.
Air Sweeper to level 3.
Air Bombs to level 3.
Hidden Teslas to level 3.
Archer Towers to level 8.
Cannons to level 7.
Air Defenses to level 5.
Air Sweeper to level 3.
Air Bombs to level 3.
Hidden Teslas to level 3.
Wizard Towers to level 4.
Archer Towers to level 8.
Mortars to level 4.
Cannons to level 7.
Spring Traps to level 2.
Tier 6Spring Traps to level 2.
Wizard Towers to level 4.
Mortars to level 4.

Town Hall to level 8.
Tier 7Town Hall to level 8.

Try to keep your walls on par and maxed before upgrading to Town Hall 8. You don’t want to drag behind this early in the game!