Clash-of-clans – the purpose of trophy pushing

You can earn gems for free in the following ways:

1. Clearing up the trees, bushes, rocks, etc. that spawn around your village. Rocks do not re-spawn once you remove them.
2. Earning achievements in the game rewards you with gems. Check your achievement progress in-game to see how many you can earn and from what.
3. Once you've unlocked your Builder Base and reconstructed the Gem Mine, it will start producing gems for you.
4. Each league season, the top three clans are awarded gems, split equally among the top 10 players in each clan.

If you don't mind losing trophies, a good strategy is to put your town hall on the outside of your base. Then using a bulkhead base design, focus all of your defenses to protecting your resources.

I typically hover around 1k trophies this way. Most people that attack me will just go for the Town Hall and leave my huge defenses alone. This gives me a free 12 hour shield when they do so as well.

Just a note: if you cannot protect your resources at Town Hall 7, then you're going to lose even more resources at Town Hall 8. The bigger the difference in Town Hall levels between players greatly affects how many resources they can take.