Always look for checks!
A checkmate is a check, but also many checks are useful for other tactical purposes, so always considering the checks in any position is important to not miss such opportunities.
Now I know it's easy to say "always look for checks" but how do you train your brain? One thing you're already doing right is drilling checkmate puzzles. Another thing that works very well with my students is the question "How many checks do I have in this position?". I ask them this all the time, and I find it an easy way to train your brain; just by counting them you're doing the exercise of finding them and at least you know you're aware of them. Some people say the first question you should ask in any position is "What's my opponent's threat?" and don't get me wrong, I think that's a great advice, but I would go on and suggest "How many checks?" should even be first 
Being aware of checks is just the first step, but an important one to not miss them. Over time, drilling checkmate patterns will help your intuition to quickly find when a check looks more promising than others.
Hello!
I've recently gotten back into chess and have been playing some games against bots. I think my openings and middlegames are decent for a beginner; my main concern is checkmating. Most of my games end during the middlegame, but I keep missing even mate-in-one opportunities.
I struggle with visualizing the pieces , and mating sequences are literally unfathomable to me. I'm drilling M1 puzzles on lichess and am going to move on to 2+ once I get good at these.
However, does anyone have any general tips or tricks for playing checkmates, especially in the middlegame?
Thanks!