Honestly, I'm not sure if there is an answer for this. I would say the best you can do is try to focus on the servants you really really want, but even then sometimes you get disappointed. I recently spent about 140ish SQ and 20 tickets rolling for Musashi and did not pull her. Worse has happened to other people I know who have played this game so i think salt is pretty unavoidable. Just try to go for the servants you really want and hope for the best.
Also to your point about CEs, yea that really annoyed me. In my rolls I got 7 copies of the First sunrise 5 star CE -_- it is what it is though