In this post, you can find a pretty accurate collection of tips related to extending the length of combo, provided by your fellow player MartinB105. Here it goes, as is:
These tips are ways to extend the length of a combo.
Assuming you’ve mastered the ability to quickly match gems, you’ll often find yourself in a situation where the play field has a lot of empty space in it after you’ve made a lot of matches, but the gems have not yet fallen.
The problem is, gems will only fall when there are no gems in the process of disappearing and you’re not allowing to swap a gem into an empty space.
This can leave you in a situation where there is a lot of empty space and no valid moves left, so the only way to proceed is to let the gems fall.
If you’re lucky, the gems will fall to create one or more matches so you can continue your combo. However, often you won’t be lucky and the combo will finish as soon as the gems fall because there aren’t any new matches.
A good solution to this problem is to leave yourself with at least one valid move near the bottom of the play field. Wait until the gems drop before making this move.
This will guarantee you an opportunity to continue your combo with a new full play field of gems.
Repeat this technique as many times as possible to extend your combo.
The reason to leave your last valid move at the bottom is that it is not possible to swap gems that are falling, therefore you must leave your valid move in a place where the gems will not be falling (which is typically closer to the bottom of the play field).
Here is another slightly more advanced tip:
As long as gems are moving, a combo won’t end, so it’s possible to keep a combo going even when you can’t see any matches as long you keep swapping gems (it doesn’t matter if the moves are not valid, as long as you keep gems moving at all times).
So, just keep swiping to swap any available gems for as long as you need to give yourself enough time to find your next match (watch out for the locked gems).
As long as you did this correctly, your combo will continue when you make your next match.
One warning about this technique: If there are no more valid moves, the gems won’t scramble until you all gems have stopped moving, so it’s possible to put yourself in a situation where you’re searching for movies when there aren’t any available, and you won’t know this for sure until you kill your combo.
If you’re quick enough, it’s even possible to press the hint (?) button whilst keeping your combo going to get the game to tell you your next move so you can continue your combo.
I’ve managed to score 943,100 using these techniques without using any bonuses or totems, by keeping a single combo going for the entire round!
I’m current at position 154 on the global leaderboard.