It's hands down the weakest part of my game and it is about repetition, just like most things, but I'm not sure it's just that.
For me it's the multi tasking in a game situation that I really struggle to translate from practicing into playing.
I look and feel okay when there aren't nine other skaters on the ice, but throw them into the equation and the need to be situationally aware and I find it hard to skate, stick handle and be aware all at the same time.
If you saw me skating off the puck or playing in defensive situations, you'd think I was a lot better than I am. I can skate, pass and shoot well enough, but throw in being on the puck and I get found out pretty quick, at least by experienced players. While it's okay at times, the consistency just isn't there in different situations. Far too many turnovers and breakdowns in the play result.
It still comes back to skating for me. I'm really happy with my out and out skating development, but it's still not instinctive enough that I can really focus my energies and attention on stick handling and situational awareness.
Agreed the skating has to be as natural as walking, in order to think the game while handling the puck. For skating, one thing to consider is getting out at public skate (no gear, no sticks, no pucks) with one of those skate training carts (ideally
the really robust ones), and just practice making tight turns/direction changes, forwards/backwards (don't ram anyone!) for 10 minutes of a 30 minute session. The cart supports you, so you can begin thinking just where you are going, without worrying about falling down. Once a week, can also work on some other drills, no time wasted on dealing with gear other than skates, helmet, gloves.
As for the puck control, obviously repetition helps. But to be more targeted, consider getting a buddy in warmup to spend a couple minutes doing a puck battle drill in a confined space. Usually the center ice circle is largely unused during pre-game warmup (watch out for Mark Messier), have the two of you battle to control a puck without leaving the circle or half circle. Really try to keep your head up, and (see toilet paper roll posts above) roll your wrists to create a "roof" over the puck with the blade of your stick.
Finally, consider "focusing on infinite" when you have the puck. Regardless of where you are looking (ideally not down), when you have the puck try focusing on infinite to avoid tunnel vision.