Tactics trainer here is great. I heard IM Pruess say that whenever you get one wrong, play the correct move a few times to solidify that pattern in your mind. He also said don't do too many at once since you brain will just be overloaded.
Best way to get better at Tactics?
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Spend no more than 20 minutes per a problem,reason the solution (whether or not you solved it or not) from a "strategic" point of view,why do you think that this tactic existed(you should ask that also before trying to calculate moves as this alone will solve a lot of problems,positions should be from real games (and not a "mate in 3" composed problems), chess endgame studies are a good source if you can solve them!
What do you think is the best way to get better tactically? (If you're going to say just do a bunch of problems, what should I do during them to get better?)