Measure how deep your lure dives at trolling speed, then position the ball so the lure will bump the bottom. Diving lures usually bounce off the bottom without snagging. Keep hooks sharp. Sharpen them every time you snag. Smelly jelly smeared on top of the lure can help produce more its.
Lighter line is better.
If you know how to play a fish, use 10-12 pound line. If you don't, use 14-20 pound. Use the Rapala knot to tie on a Rapala. The knot leaves a loop in the line that allows the lure to move freely. Don't use swivels or rings with a Rapala.