The proper speed for trolling depends on the species of fish you're targeting and the type of lure or bait you're using. As a general rule, most trolling is done at speeds between 2-6 knots. To maintain the proper speed, use a trolling motor, or adjust the throttle on your boat's engine. You can also use a GPS or fishfinder to monitor your speed. Keep in mind that the speed of your trolling will affect the action of your lure or bait, so adjust accordingly to maximize your chances of hooking a fish.