the big problem with you is you do not trust yourself, you are not tough enough. if you shorted a rally and think it will go down, then calm down and sit there tight, even against you, if hit margin call or hit your loss limit, get out. ok, no problem, next time, see a huge rally, just do it again, trust yourself, not every time you will get hit, market extreme does exist, but will not last very long. I once bought BSC in the biggest drop, and lost 60% of my account, but I rebounced quickly from buying biggest drops like WM, ABK, cal, VNDA...., shorted HYPE like VMW, JOYG, ICO, even shorted WAVE today, who cares " catching the falling knife, buck the trend, avoid the opening, avoid earning..." all those wisdoms are just sheep's wisdom (doomed to be a loser).
rules are not necessary, the most important thing is you must trust yourself, you must know what you are doing, know when to get out either wrong or right.