well to do well what you wanna do is to try and get a toil and trouble at each pass. (that means 3 different colours at each time) filling as many bottles at once doesnt get you hardly any bonus unless your doig like quicksilver. if you keep getting toil and trouble then you should maintain an excellent standard fill. on bigger bottles this is effective.. if by filling a fire burn (4 colours), you can always do a sinlge coloured bottle within that pass and it will be 2 star automaitcally...
when and if you get a quicksilver, that is when you wanna try and fill as many bottles as possible, filling all of them will get you an incred most likely.. dpending on your performance up to that point.. but will get excellent for sure..
i might add that toil and trouble can take practice for beginners. and to maintain it.. try to look at the board carefully and move when necessary rather than going straight in.. sometimes you can run out of moves when you didnt have to.. good luck!
pm in game if need advice on particular areas.
My stat in puzzle is ultimate on hunter.