I have a great strategy. In fact, it is more of a money management strategy. Here it is: I call it "fixed profit".
Here you define the fixed profit you wish to receive from any bet, and calculate the stake amount of money for a particular bet according to the formula:
(your fixed profit) / (odds - 1)
I.e., if you wish to win 10 units every time, then for odds=1.8, you should stake 10/(1.8-1)=12.5 units, and if the odds are 2.5, you should stake 10/(2.5-1)=6.67 units, and so on. Don't worry if the odds become lower as you receive your desired profit anyway (of course if you win).
I found mathematically that if you use flat betting (with fixed stake of S1 units) and fixed profit (with fixed desired profit of S2 units) together, then for odds lower than S2/S1+1 (in decimal (European) notation) you should use fixed profit, and for odds greater than or equal S2/S1+1 you should use flat betting to maximize your winnings in the long run.
I use this combination and can tell you that it is very good indeed.