Pull weeds from the planting area. If there are too many to remove by hand, kill them with an herbicide. Apply it two to four weeks before planting grass seed. Follow the instructions on the label. The chemical will kill any green vegetation it touches, so only apply to the areas where you plan to put grass.
Spread at least 2 inches of sand and topsoil on top of the muddy area. The amendments will dry out the moisture and encourage better drainage. The exact amount of sand and topsoil depends on how muddy the area is.
Incorporate the sand and soil into the mud with hand tools or a rototiller. Add more of each amendment, if needed, to make the mud into fertile soil. Work the soil to a depth of 4 to 6 inches. Rake until the yard is smooth.
Spread an inch of compost on top of the amended soil. Rake until smooth. The compost adds nutrients to the soil so the grass seed takes.
Fill a hand spreader with seed if you're working on a small area. Use a mechanical spreader for larger yards. Use a seed calculator or the information on the seed bag to determine how much seed to use. Walk over the yard, row by row, dispersing seed.
Drag a metal rake over the grass seed to mix it into the top 1/8 to 1/4 inch of amended mud. The soil will keep the seed in place, prevent birds from eating it and encourage faster germination.
Water the seed to keep it moist. Twice a day for five to ten minutes should suffice. Keep up the schedule for ten days, then cut down to one watering session per day.