Practicing over water is good because you get that visual feedback as the weight hits the water.
That's the moment when you have to HIT THE BRAKES (stop the spool) or you'll have birds circling your location as you pick out the bird's nest.

So to reiterate....

Set up the Shimano with two brake weights engaged (the side plate must be opened)

Add in a little spool shaft tension (the little round cap) so your weight can fall to the ground in a controlled manner. Not dead slow, but not brisk enough to bird's nest.

Start with heavier weights and slowly work down to your preferred weight.
Don't go for the homerun cast. Work your way up in applied power.
Your best casts come from a smooth, pure motion and accurate thumb work.

As mentioned above, choose a rod that will load properly with your preferred weight.
This is key to getting good, efficient casts. Utilizing the stored energy in the loaded rod means less wear and tear on you.

Coming from spinning reels, it took me a season to get comfortable with my first levelwind.

Edit:
Just as in auto racing, NEVER LIFT