Using a starter fertilizer or organic fertilizer during seeding will help the grass germinate and develop roots faster. The food adds necessary nutrients, like nitrogen and phosphorus, into the ground.
Laying mulch on top of grass seed will keep weeds away and retain moisture and temperature. Straw and hay make good mulch. You can remove the mulch when the grass seeds sprout, but you don't have to.
If weeds emerge, you need to treat them or they will steal nutrients from the grass seeds. Most chemical weed control products will kill young grass, so don't use them until the grass has been mowed three times. The only one that can be used is siduron, which is a pre-emergence formula.