In puzzle RPGs like Gems of War (which I have spent countless hours playing), or Puzzle Quest (which I have yet to play, unfortunately), it may seem at first that some of the main keys to successes are luck (particularly since what falls after a match is made is random) and grinding to level up. But this is not entirely true; rather, I believe that there is much more than what meets the eye when it comes to games such as these. A strategy should be a key component to the player.
Of course, there are troops you can obtain and level up, but it is in the arrangement of these troops that matter.
For instance, if you know an enemy can deal damage that ignores your armor, opt for a team that has high health. Knowing your adversary's strengths reveal how you should arrange your team and how you should play. Moreover, this idea of arrangement is key when playing PvP, where the team you will face may be as strong, if not stronger, than your own. What should I put in the first slot, (the troop that receives most of the damage) until it is killed? Perhaps a troop that can increase its attack, to quickly knock out the other team. Or, perhaps one that can heal itself, helping ensure the rest of his or her team to fight with for a majority of the match. When paired with a troop that deals DoT (damage over turns, in this case) by poisoning or burning the enemy this makes for a lethal combination.
There is yet another crucial component that makes for good strategy, and that is setting up your moves. After awhile of playing against the AI (which you will, even if playing PvP, based on how the game is set up), you will find it easier to guess what move the AI will make, based on the move you just made. If you make a match that allows for a 4- or 5-gem match to be made (which gives you an extra turn and a mana boost), the AI will make that move, nearly 90% of the time. Hence, in a way, the game is similar to chess in this respect. If you can recognize that matching these gems will cause a cascade of other matches, it is often best to perform that move; this will require practice, spatial reasoning and taking a time to find the best move.
These strategies have helped me win battles against teams stronger than mine (higher levels, more health, and so on), where victory was doubtful. Hence, playing games like Gems of War is not simply an exercise in grinding to get more resources and level up, but also an exercise in employing strategy on a virtual battlefield. I would recommend checking it out for anyone who enjoys RPGs that depend on strategy to be victorious.