Depending on your familiarity with tactics, I would suggest starting with non-random tactical puzzles. Drill one motif over and over again until it becomes second nature, and then move on to the next one.
My fastest development came when I read Tarrasch’s ‘The Game of Chess.’ In the Middlegame section, he goes over many tactical motifs in detail. He starts with the most basic pin on a near empty board and how to take advantage of it. He then adds more pieces, then more pieces, and soon the examples are quite complicated … yet understandable. He ends by showing how it’s possible to sacrifice material to set up such a pin, and it doesn’t seem magical or mysterious at all.
Once you know all of the tactical motifs, it makes sense to train them randomly, because you never know what tactics may or may not be available in a real game. If you want to learn and reinforce the patterns, though, themed tactical puzzles are an excellent way to start.
"All the training will be done with a real board."
McDirtalot, when going over Master games, I've heard of using Two boards. One board is for the game, the second board is for all the unplayed variations. Do Guess the Move for Active Learning.
However, I do puzzle over some things I've been told. Guess the Move and Active Learning is time consuming. Some very good players don't do that. They click through many games rapidly, and they say they acquire pattern recognition faster by their subconscious. They say you have to acquire tens of thousands of patterns. So they do the clicking to get those patterns quickly in their brains.
Seems like both ways work.