I think dont exist 100% safe strategy on dice.
You need to use dice sites for fun this is the best strategy

That's why I said "relatively safe", god.
Mathematically a single martingale sequence is the best and safest way to play on any dice site no matter what house edge, you can find more details on the "does martingale really works" thread.
Other than that all the strategies are the same, literally they all suck equally
What about this:
Chance: 30%
Payout: 3.3x
Base bet: 0.0001
If you lose one bet do the same amount again. If you lose your 2nd bet increase amount by 2x and again. So if you are unlucky and losing, it will be 0.0001, 0.0001, 0.0002, 0.0002, 0.0003, 0.0003 until you win. This wouldn't work if you have really long loss streak, because it won't give you back the full amount you spend on betting, but with up to like 8 bets it can make good money. What do you think about this strategy? Somebody was talking about this in the Rollin.io chat.
Unfortunately that strategy is no better than martingale or any other strategy.
Lets say you have 0.01 bitcoins and you start with your base bet, you would need to lose 19 times in a row to bust, now that seems a lot, but is it really? Lets see:
The chances are 0.0060935974001% or in other words 1 in 16.000~ so every 16k bets you are theoretically loosing 19 times in a row, the money you get before the bust its not enough to cover the 0.01 loss, this happens with martingale as well and all other strategies.