Weed control starts with turf care, not a spray bottle. Thin cover, bare soil, mowing stress and compacted areas create opportunities for weeds; treat the plant in front of you, then remove the condition that allowed it in.
Identify before you treat
Take a clear photo or keep a small sample for identification. Weed species and turf varieties do not all respond the same way. If you choose a herbicide, use only a product registered for the weed and lawn you have, and follow the label exactly.
Keep the lawn competitive
Mow at a sensible height for your grass type so the turf can shade the soil.
Avoid scalping: it weakens the lawn and exposes soil to weed seeds.
Repair bare or compacted patches rather than repeatedly treating the same opening.
Use treatments deliberately
For isolated weeds, hand removal or a carefully directed spot treatment may be enough. For a larger area, confirm the weed, turf type, weather conditions and label directions before you apply anything. Do not make application decisions on a hot or drought-stressed lawn unless the product label permits it.
Record the product, rate and date, then check the result before repeating a treatment. Good weed work is deliberate, measured and followed through. — Lenny, Greenkeeper