How do I gain levels quickly and effectively?
Experience is gained by performing different activities in game, such as upgrading buildings, completing achievements, donating troops in clan, destroying town halls(by raiding) etc. The more experience you gain, the higher your level goes.
To answer your question, the most effective and quicker way is by upgrading buildings. The buildings particularly the defense buildings are those which actually allow you to safeguard your town and collected resources. Further the saved resources (by raiding and collecting from mines both) allows you to upgrade more buildings.
Achievements whereas do give you quite a lot of experience as well as gems but I won't consider it the quicker route as it takes a lot of time to literally complete some of the achievements. Whereas destroying the town hall while raiding only gives you single-digit experience.
Moral: Raid more > Collect more resource > Upgrade buildings.
P.S- Experience level does not define you as a GOOD or a PRO player.
Hope this helps. :)
Clan hopping is the best way to level up. I levelled up 17 levels in a day all from clan hopping. Clan hopping is when you join a clan, donate all that is possible, leave then join another clan. When you donate, depending on how high your troops are, you get Xp. It's a great way on how to level up.
Since I joined clash of clans I have gained my experience, And have found a few ways of levelling up. One, is clan hopping, where you join a clan, donate all troops which are needed in the clan, leave it and then join another one, carrying on with the same idea. This really helped me, And i levelled up about 9 levels in 2 days or so, so I advise you to use this! The second one is to get gold and elixir, what you can do is use your gems to give them a boost, so you earn double the amount for 24 hours!
The best thing is to upgrade your collectors and mines also the defence and army as much as possible and donate many troups as much as possible . To donate troups train the high spacing troups like dragon and join any clan ,so that u'll get a troup request .Donate them and join another clan.This is the best way to get level up..!! Good luck!...clash on..!!
Fastest way for me is joining a clan, donating and leaving it. I joined some last night and now I have over 1,000 donations. I leveled up about 3 levels and I know I'll level up a lot more :) Hope this helps, but as others said, I would also upgrade defences and eventually you will get gain some achievements without even trying! Haha.