Chances are that you are a newer member to the clan and you don't want to mess things up here. Well you have come to the right place, please read ahead to avoid making any major mistakes that could take you out of war for a prolonged amount of time.
As a TH7/8 you could pretty much get away with not being very good. Most of the time you can just spam your army at a base and three star it without much planning or consequence for failure. Also, noone really kept tabs on your base design or tower upgrades etc because, to be honest, we just don't care enough and have very low expectations of anyone below TH9. Not that we don't care about you, in fact we care a lot. But, war results simply dont have much bearing below TH9.
As a TH9 you are just now approaching end game. Hahahaha, no not because your almost done maxing out and beating Clash of Clans. You probably have about 2+ years left until then... Wall and hero upgrades alone will seem impossibly difficult to complete, and current research times mean that you will be TH9 for at least 6+ months. Therefore, we cant afford for you to make a mistake now that will take several months to correct! In other words, your choices are begining to have consequences.
So, lets try to get you off on a good start. It is possible to hit TH9 running and within just a couple weeks you could have a sizeable advantage in war. In order to do this I have outlined some tips and tricks to make you one of the most sought after players by war focused clans in the game: a stud TH9!
1. I started to upgrade my townhall, what should I do now? Noone should be starting TH9 until they have maxed their research (or all but one, see below under laboratory upgrade) and maxed their barb king. Once your final research is underway (or 2nd to last) you can start the townhall upgrade. Ideally, your research will finish before the townhall upgrade is completed. While your townhall is upgrading, it is crucial that you max out your storages. You are gonna need every coin and every drop of elxir. Ideally, you will also have full treasury. If you are a super badass, go ahead and buy all the decorations as well so that you can sell them back for more loot once the townhall finishes. To be fair, dont bother with the elixir decorations...
Total available loot for use if maxed at TH8:
Gold: 7,000,000 gold storages + 750,000 townhall storage + 1,200,000 treasury + 400,000 decoration sell back = 9,350,000 gold total (maximum)
Elixir: 7,000,000 elxir storages + 750,000 townhall storage + 1,200,000 treasury + 6,700 decoration sell back = 8,956,700 elixir total (maximum)
Dark Elixir: 75,000 dark elixir storage + 6,000 treasury = 81,000 dark elxir total (maximum)
2. My townhall just finished upgrading, what should I build/upgrade first? At this point we have to assume you have 5 builders. If not, then you wasted your gems up until this point and shame on you!
1st builder - Build your Archer Queen/AQ! Congratulations, you finally have an Archer Queen! Good news, this is an instant build and she is immediately available for use! So go ahead and raid with her right now! Bad news, once you finish that raid you have to put her under upgrade... Sorry guy. (Instant + 12 hours)
Total cost: 40,000 dark for AQ level 1 + 22,500 for AQ level 2 = 81,000 dark elixir total - 62,500 dark elixir cost = 18,500 dark elixir remaining (in 12 hours you will need 6,500 more dark elixir to start level 3 for 25,000 dark elixir, so start raiding)
2nd builder - Begin upgrading your Clan Castle (6 days). Yes, you can still request troops etc while it upgrades.
Total cost: 9,350,000 gold total - 4,000,000 gold cost = 5,350,000 gold remaining
Free builder - Use your remaining gold to build and upgrade all your traps (seeking air mines x2, giant bomb x1, and new walls x25 (all instant). You should then be able to upgrade all 25 to level 6, and 11 of them to level 7.
Total cost: 5,350,000 gold total - 5,226,250 gold cost of walls - 42,500 gold cost of traps = 81,250 gold remaining
3rd builder - Begin upgrading your Spell Factory (5 days). **Or gem it complete. Spell factory upgrade time is one of the few items worth gemming outside of hero upgrade time and boosting barracks. This is because it can be awful to raid without spells.**
Total cost: 8,956,750 elixir total - 1,600,000 elixir cost = 7,356,700 elixir remaining
4th builder - BEFORE you begin upgrading your Laboratory (5 days), be sure to begin a new research. If you left one reasearch at TH8, now would be the time to start the final TH8 research. This is because the research time will still run while the building is upgrading. If you decided to gem your spell factory complete, you can get a head start upgrading Jump to level 2 instead! This is because level 2 Jump only requires a level 6 Laboratory which was upgraded at TH8, but it doesn't unlock until you finish upgrading your Spell Factory. Side note, once the Laboratory finishes upgrading you need to log in, log off, then log back in. This is because the game is glitched and will show that your research has not completed when it actually has until you log back in.
Total cost: 7,356,750 elixir total - 2,500,000 elixir cost = 4,856,700 elixir remaining
5th builder - Begin upgrading your Army Camp (5 days).
Total cost: 4,856,750 elixir total - 2,250,000 elixir cost = 2,606,700 elixir remaining
Bonus builder** - If you decided to gem your Spell Factory as noted above, then you still have an extra builder available which can then be used to upgrade another Army Camp (5 days). Alternatively, you can reserve it for your next AQ upgrade to level 3.
Total cost: 2,606,750 elixir total - 2,250,000 elixir cost = 356,700 elixir remaining
3. Ok, its been 5-6 days. What should I be upgrading next?
Elixir - As your builders free up, you are going to want to prioritize upgrading your remaining Army Camps ASAP to complete having TH9 strength offense. So spend all your elixir on Army Camps and then go ahead and start building/upgrading your dark elixir drills, barracks and dark barracks, dark spell factory, and finally sink it into walls. Meanwhile, you will likely need to save some for researches as well as you go. Elixir will be a major focus of your raids along with dark elixir.
Gold - Use all your gold on trap upgrades and go ahead and build the 4th air defense and 2nd air sweeper, this way you force the enemy to attack you with ground troops instead of dragons. Most new TH9 still use dragons for war and this will give you a lot of defenses vs them and max TH8s that are tempted to attack the 'baby TH9.' Then dump ALL excess into walls. Do not bother upgrading or building any new towers intially. As you level your research and heroes you can choose to upgrade and/or build towers. A sensible guideline (assuming you are able to 3 star a similar base in war) is no xbows before 10/10 heroes. No max xbows until 20/20 heroes. Fortunately, gold will never have to be a focus of your raiding, its all just bonus for wall upgrades.
Dark Elixir - Use all your dark elixir to push your Archer Queen to level 10 ASAP. You should then try to upgrade BK and AQ at the same time while using what you need for relevant researches. This is because as hero upgrade time approached 7 days per level, you will eventually ALWAYS be upgrading at least one hero. In turn, you cannot war without both heroes and raiding is hindered. The hero grind is very painful and very rewarding... So by waiting until you have enough dark elixir for both heroes, you have time to fit in more wars. Albeit, you will be going a week at a time without any hero for raiding, but that better than always having only 1 hero and rarely warring.
4. Why is it beneficial for the clan if I don't upgrade my current defenses or build new or stronger towers? This is because clans are matched based on their clans overall war weight. Every building, research, and upgrade increases you individual war weight, which is then added to each of your clan mates that are currently in that war. Defensive towers are weighted most heavily. And, not surprisingly, stronger towers like eagle artillery, inferno towers, and xbows are weighted much heavier. Its good to note here that your war ranking is reflective of your defensive weight ONLY. While offensive upgrades such as research, barracks upgrades, and heroes also increase your war weight, they are weighted less heavily than defenses. In addition, like upgrading walls, the benefit of having a strong enough offense to 3 star enemy bases with both attacks off sets the additional weight given to your base in match making. Worst case scenario, your shitty defense and high offensive weight ranks you somewhere in the lower middle and the enemy earns 3 stars. BUT, your offense can earn us 6 stars versus their upper middle and top! 6 stars vs upper middle/top > 3 stars vs lower middle! Go math!