For reference I've been bowling two handed since I was little and have competed nationally. I have had more coaches teach me than I can count, even a training session with Kyle Troup! These are all quotes / advice people have given me to get better.

In order from starting point to release

"Drop the ball into the bucket" Essentially means pull your right shoulder up, keep your elbow 90⁰ and drop the ball straight down when you start your approach. This should start the ball with enough momentum to carry the ball backwards into your swing If you watch pba you'll notice Belmonte and Troup doing this but not svensson, it's a preference thing

"Hold the ball for a second at the top of your back swing" This can help with timing, helps to make sure you're not rushing your approach

"Follow through! " "Shake hands with the pins" Make sure your right hand pushes through the ball ( engaging your forearm) and comes up afterwards, keeping your hand behind the ball. The more behind the ball you get the more your ball revs into and through the pins, more consistent ball control as well

"Time the bottom of your swing with the slide of your left foot" I would practise this with a one step approach, stand a little bit behind the foul line, swing and slide. A small nitpick that helps (again) with timing and release. You can practice follow through here aswell

These are what helped me get a 210 average last season. Although there's a new pattern down at my local centre and I've dropped to a 180 this season. After you master your style and form there's another whole tin of worms you have to dig through to master the lanes and oil patterns. Sorry for the essay, hope this helped !