I will not see over what is your roll and what amount of bet per satoshi , because here any method you will choose will not work for the earnings easily at this website .
Since this website is most trusted website but still I will never say that it will be easy for us to make gambling , because this website about cheat us in gambling game .
Once I was making gambling at this website with 0.3btc ( about 2 month back ) , I was placing my bet with a stretagy but continuously my 23 bets get results into loss .
It was really a sadful thing for me that I lost this amount due to only cheat , here 0.3 BTC is not a small amount and continuously lost in bet by 23 times is not a fair thing for me by freebitco.in .
So leave your stretagy of gambling hi-low etc , all these works with few limited bets only and for small interval of time .
Actually any amount will give the same result, it just matter of chance whether you are going to win it or not depends on your luck. Any gambling strategy will just be the same too because of the house edge, you can never get out from it. On your case you can't say that freebitco.in is cheated your resuly because they have provably fair system which you can fair result. But you have suffer many losing streak probably is because of their 5% house edge. This is why most of gambler stay away from it or never usr any strategy, just manually gambling, it is much safer