When you are depending on that graph you need to have a more time so you can really manage not to lose money in trading and save some extra bitcoin in the next dont panic when the price is low wait for it always to be high again and everything will be fine.
waiting for the price to rise high sometimes just working is it does but i'd prefer to cut lose if the specific coins seems don't have a good future to prevent from having such a big lose like zcash which had been falling down recently from 1btc to about 0.3btc and that's such a pain in the ass
Lol, my strategy is to buy a bitcoin when there were negative news and the price dropped as a result of bad news. Then holding it for a couple of weeks and sell it out when hit the higher price. Its all people know this. I guess unnecessarily this discussing about this further.
but by using your strategy you must be prepared because if the coin get really bad news that could affect the entire system of the coin,people would lost interest of the coin and maybe there's no one buying on the market,as a result,your funds getting trapped into the coin's market,be careful with that strategy
There's not fix method here because it's the actual market and you need to update yourself with the right information. Buying every time it's low is not a good idea as it does not work all the time.