If things aren't looking good for one of your towers and your opponent's making a major push that way, consider sacrificing it and sending loads of units up the other pathway.
As long as you don't risk your King's Tower in doing so, this can keep a game alive, rather than you losing one-nil.
Timing is everything. Matches are three minutes long, but during the final 60 seconds, elixir regenerates at double speed.
Time attacks to align with this surge and you can cause serious damage. Also, if the score's level but an opponent has a very weak tower and you're armed with a projectile (like a Fireball), defend until the last few seconds and blow up their tower in the final moment, ending the game and stopping overtime. Clash Royale Hack
We touched on this earlier with swarms, but with every attack you make, be aware of the elixir trade. There's no sense using expensive projectiles to take out low-cost troops, but also be watchful for powerful lowish-cost units.
A high-level Valkyrie can rampage through a number of troops and annihilate weaker swarms (such as an entire Skeleton Army) unscathed. Free Clash Royale Gems