I would suggest placing 1-2 seed into a 3 or 4 inch starter pot , plastic planter ,etc, 1/4 inch or so apart into potting mix prepared to a measurement of about 80 % full . then lightly place additional mixture over top to about 1/4 " and pat to neccessary setting water very lightly . however, lettuce is a plant that needs watering more often than avg.Also they should germinate within 6 -8 days. good luck
All Lettuce types are a cool season crop. Plant in January - March. we just make a small raised row about 4 inches taller than our garden and about 1-2 foot wide. pinch seed in finger tips and sprinkler as if adding salt to a dish. (12-14 inches above planting area.) repeat for several pinches. Using a small hand rake or a fork, gently rake soil around over seeds. water lightly. keep moist for 1st couple of days. after sprouts start to emerge, pinch out the tight areas and allow a little room between each plant. (leaf lettuce). in about 3 weeks, start cutting and using lettuce.
Heather, you'll have to get used to sticking your finger in the dirt to find out how often your lettuce needs water. There's no chronological formula. If the soil is dry down to a couple of inches, it's time. Harvesting depends on whether you have head lettuce or leaf lettuce. Leaf lettuce can be cut any time after it has reached a decent size. Head lettuce should be harvested when the heads are firm but not hard. Clyde is right that it's a cool season crop. Our lettuce season has already been over for awhile here in Florida.
Lettuce is a cool weather crop, but you can plant them in the shade and coax them if it's not too hot where you live. Since your weather, in MI, has been cooler this year, you may still be able to plant and harvest some baby greens. Just purchase some mixed lettuce and broadcast it in a small area, like a 2 X2 space, don't worry about it being crowded since you will be cutting it in the baby stage which is about 3 or 4 inches tall. It should be ready in about a month.