How do we set our stop los and take profit ?

Normally as price action traders we simply look at different support and resistence areas…

We draw some lines, some boxes and boom… We can set and calculate a good risk/reward ratio.

But how do we choose good stop loss and take profits levels when we cant "see" them ?

Well we actually could simulate the drawing or find areas where candles concentrate, but isnt this a bit too much ? Arent there easier ways ? I am glad for every help on this topic 🙂