General rules for lawn care: * Healthy grass will crowd out most weeds. Thick turf keeps light from reaching the ground, which keeps seeds from sprouting. * Fertilize on a regular schedule. What that schedule is depends on where you are. Whether you use organic or conventional fertilizer is up to you. * Many weeds are killed simply by mowing them repeatedly. Keep the grass mowed to the proper height.
- Find someone local who will give you plant advice. The nearest nursery might have a master gardener who will advise you in return for selling you stuff.
- Get your soil tested. That will tell you what you need to add.
- Based on the test, add the needed nutrients (fertilizers).
- Mow to the right height.
- After two mowings, see what weeds are left. Take samples to your local guy. He can recommend weed and insect killers.
- Keep this up for a year. Your lawn will look much nicer.