This was the main focus of my riding for ages after going on a skills course with Jedi a few years back, he said he always knew when I was braking in the corners as it brings the bike back upright apparently (which is the last thing you want!)
A few things that help me: look at the exit not in front & set your body up for the turn (i.e. hips pointed in the direction you’re turning – driving with the hips through the turn really helps me tighten the turn). Pushing the bars down into the corner with your inner arm to lean the bike whilst keeping the body upright so you can use the outer knobblies on your tyres (essential if you’re running a Rock Razor or similar!)
Having the saddle out of the way is handy if there’s a series of turns/berms as you have to move your body position over to the opposite side ASAP. I find the bigger, more dynamic the movement & the harder I can push with arms/legs the tighter/faster I can turn which is essential at speed – don’t just cruise round corners!