How can I improve in coc?

I see you've used up your gems on who-knows-what. Save them for builders, 4 is a good amount.

Like someone else said, keep your trophies low for now. Trophies don't pay for upgrades. Start moving up in trophy count when you hit upper TH7. By that time, you'll need DE (dark elixer) and the only way to get it is by raiding higher level bases at higher trophy ranges.

Use cheap troops for raids, barbarians and archers. Maybe a WB here and there and a few gobs to get to storages. Try not to use spells in your raids, they cost too much for farming.

Make upgrading your troops (via the laboratory) and army camps your first priority. Strong troops will make raiding easier.

Don't rely on going after just mines and collectors, go for storages too. Otherwise it'll take forever to build up your base.

While raiding, if your troops seem to do unexpected things, pay attention to what they are doing and experiment with how you're dropping them and how you're using them. The game's AI can be a little quirky, but it can be compensated for to some extent.

Number One Tip! Do NOT go up in town hall level until you've maxed or nearly maxed everything. Otherwise, the loot penalty will kill your progress.

Study the information here and get smarter: http://clashofclans.wikia.com/wiki/Clash_of_Clans_Wiki