Upgrading

After Town Hall (TH) 4, it is very important to start upgrading everything before moving on to the next TH level. It is extremely important to absolutely max everything before moving to TH 7 (see war requirements below). The only exception to this would be collectors, those are not as important because you can raid for loot.

The reason for maxing out everything is two fold:

Firstly, there is a loot penalty from lower TH levels. This makes raiding extremely hard if you rushed your TH without upgrading everything else first. This has actually destroyed accounts before with very little chance of recovering from it because any enemy TH of equal level cannot be attacked effectively and they can raid the rushed account for huge amount of resources. For information on how to recover an rushed TH, see this link.

Secondly and more important, a rushed TH can mismatch the War search results. The entire clan depends on the war for both fun and loot. When a rushed TH is thrown into the search, it can go against a normal base with the same TH level. The same problem occurs as with raiding: The rushed TH doesn't have the defenses to sustain attack from the enemy and is limited on effective attacks itself.

An extremely rushed TH will be excluded from the War search until the problem is corrected. If anyone needs guidance on this, ask for help. The clan would be happy to include anyone in wars that has corrected a rushed TH.

War requirements
Max all buildings before moving on to the next TH level (a few walls just below max are fine). When reaching the next TH, buy all new buildings and upgrade them to at least 2 levels below your last max. For example, the max Archer Tower for TH 6 is level 7 so the new Archer Tower at TH 7 needs to be at least level 5. New walls should be one level lower than the old max.

Further requirements of TH 7, TH 9 and TH 10 are as follows:

TH 7 must either have a viable Dragon or Balloonion strategy to war. Both strategies include having an upgraded Spell Factory. You can either get a barracks to produce Dragons or upgrade Balloons and get a Dark Barracks.

TH 9 must be able to do a viable 2 star strategy and be working on a 3 star strategy. Certain defenses and offenses need to be maxed out before warring. These include all Giant Bombs, Camps, Spell Factory and the Clan Castle. The Archer Queen needs to be at least level 5. All troops must be max for TH 8 (certain troops, like goblins, are exceptions). After the minimum requirements are met, you must be actively working on leveling up both royals (Queen is most important), Golems (lvl 3+), Valks (lvl 3+), Dark Spell Factory (lvl 3), Balloons (lvl 6), Hogs (lvl 5) and Lava Hounds (lvl 1+). For more information on where to go from the minimum requirements, see TH 8.75

TH 10 must have all Camps and Spell Factory maxed. Must be working on war strategy troops as much as possible.

Links
TH Quick Reference