I checked into the image link you provided and your technique seems very interesting, but based of the fact that crypto coin market is so volatile and unpredictable at times id say there is NO Safe/Sure method. If its working for you so far stick to it! just dont put more than your wiling to lose into it.
To keep things simple and to the point I personally do crypto trading old school style which simply means to watch the coin I want to invest in for few hours/days to get a true sense of its current value. then I try to "Buy the Dip" (Buy/Invest in coin at lowest point I can invest after watching coin value go up and down over watch period)
I also use an old trick called the Elliot Wave some say its outdated but works fine for me.(Never worry about what others say if a method works for you!) That along with researching events aimed at promoting crypto coin and also when a coin will be merging/partnership with other well known Business/establishments. Those methods give me the right balance to buy , sell and profit doing long and short term trading.
From time to time I get reliable information on which coin to buy into as it may pump soon... (This method is fastest way to lose your money) Do Not rely on this method and if you take a chance proceed with caution.