In addition to these 10 great tips, here are some of my observations from having played a decent amount of Clash of Clans now.
1) Learn the wallbreakers AI as best you can, as they are the key to an attack strategy (especially when using giants). They will aim for weaker walls when possible, but generally they will try to blow up whatever is closest, which in a good base won’t be an ideal opening. This can be countered by using 1-2 breakers on the first wall, and then following shortly after with 2-3 more to open the wall you really want. Once you get the hang of their AI, you can use them to really guide your giants around a base, greatly improving your chances of a successful raid.
2) Similarly, learn the giants AI. They are easier as they will attack the closest defensive structure, but good wall/maze placement can really reduce their efficiency. AoE (mortars and wizards) are their main counter, so you will want to open up holes to those defenses first if possible. If using in combination with healers, take out the local air defense, but then also try to get the giants away from a lot of the defenses to give your healers a little more time to heal them up. Done well, this can be almost unstoppable.
3) Keep the two tips above in mind when designing your base. Try to create something that is difficult to exploit with only a few wall breakers, while also making sure giants can’t easily move around and soak up all the damage. Trap placement is key here, especially spring traps. The best way to refine your base design is to watch replays of attacks against it; see where people like to deploy against you, see how the AI moved attackers around your base, and try to move things around as needed. No base is impossible to raid, but the harder you make it, the less people will try.
4) During clan wars, if you are a stronger member of your clan, wait until later to use your attacks. Let your newer/weaker players attack who they can get stars off, and then come in after to clean up.
5) Whoever in your clan has access to the best defense troops (high level wizards work best) should be filling the clan war defenders first. If you are a newer player, don’t put your low level troops in. Also ask the higher level players to give you a dragon if possible for attacking. Especially against weaker bases, one high-level dragon can make a major difference.
6) Buff spells (healing, rage, etc) work best when used on the most troops possible, so don’t wait too long during a raid. Dropping a heal on 5 giants who are all red isn’t going to help you as much as dropping it on 15 who are currently taking a bit of AoE damage (especially if you are not using healers). Rage is the same way; the earlier you drop it, the more troops you are going to buff, which will mean they all help destroy the base (and defenses) that much quicker, reducing future casualties.
7) When attacking, the first thing you should always do is draw out the defending troops. Just drop a single archer or barb close enough to the castle to spawn them, and once that single unit is dead either drop your lighting spell or use another single troop to pull them out further. Wizards are great at taking out clumps of units; use this offensively, and beware of it when attacking, especially since wizards will survive a lighting spell.
8) Visit the villages of your clan mates to get ideas for base defense. Watch linked replays, and if you have a good example, link your own.
9) Upgrading defenses is more important than upgrading walls, especially once walls start costing a lot of gold (75k per wall). Don’t be tempted by the quick, cheaper option of walls, save up for defensive upgrades.
10) Finally, once you have access to heroes, take the time to figure their AI out as well. The barb king loves hitting everything on the outside of a base, often walking into defenses and getting himself killed for little gain. If used correctly, he can be a huge boost to an attack, but he is harder to use than most options. Also don’t forget to upgrade him as well; it takes a lot of dark elixir, but it’s very worthwhile!
If anyone has additions tips/suggestions, feel free to post them in the comments section. Happy raiding!