One of the first most important and fundamental thing for any trader to do, is to properly define price levels on chart.
Dealing with Bitcoin price in 2019 you can witness it's peak near 20 000 price range and as price went down by now to 3750 area, this means most traders will set their levels at closest round numbers like of course at the middle 10 000 and lower 5000 level.
Second important levels are intermediate primary like 2500 and 7500 which are calculated by dividing main levels in two, and finally you get secondary intermediate levels 8850, 6250, 3750 also calculated by division in half. As you can see on BTC chart these levels work out perfectly well.
Setting levels is a very simple part of TA, but it gives a lot more comfort and vision, when making trading decisions.
Good Luck