Best strategy is not to kill every single chain as soon as possible, but assemble in a way, that when you brake something on top everything collapse and you get lot of combos. So problem is in assembling whit this combo strategy. It is also important that there is probably better to make 4 combos whit 5 peaces that 5 combos whit 4 peaces (but i am not sure, check whit scoring)
You should build big structure that allows this super combo moves. When building this structure you have also problem, that you do not know, which peace you will you get (except for next peace), so there is little probability involved.
This is very interesting problem.
You can apply:
Dynamic programming to check the current score.
Monte Carlo for probability needs.
Little heuristics (heuristics always solve problem faster)
In general I would describe this problem as optimal positioning of peaces to maximise probability of win. There is no single strategy, because building bigger "heap" brings greater risk for loosing game.
One parameter of how good your heap is can be "entropy" - number of single/buried peaces, after making combo.