I dimple the lid down while holding the side of the lid with my middle finger and thumb, then slightly try to twist it from side to side to make sure a good tight seal. Then spin the lid down snug, then give it a tight extra twist. Thus, pretty tight, though I could crank it down slightly tighter, but not much is possible.
Edit: as others mention the pressure *ping* That lets me know I have a good seal, and I hope all of my jars achieve this, it sure seems like they usually do. My regular daily rotation jars probably lose a little on the seals, but still seem to pop from time to time. Also you can get a box of new lids quite cheap and keep on hand if the time for a new seal comes. I've only use a couple to replace a damaged case of jars I bought where a few lids had a dent on the side. The damaged box was a great deal on quart jars at walmart where one jar was busted inside the box.