Summarize this article in one sentence.
If you have old grass or weeds, remove these before laying a new lawn. Use a grape hoe, also called a grub hoe, to remove grass from small lawns. For larger lawns, or to save time and effort, rent a sod cutter from a tool rental service.  Grass may be easier to remove when the soil is moist. If using herbicides, follow all product safety information and allow enough time for the herbicide to break down in the soil. Most modern herbicides such as 2-4D and glyphosate (Roundup) will break down within three weeks if used correctly. rade the soil. Grass seed will grow more evenly and root more firmly on relatively flat soil. While sod (turf) can be laid on slopes, grading soil is still recommended for flatter areas. To promote good drainage away from buildings, grade soil to a 1 or 2% slope away from a building. In other words, the soil should drop 1–2 feet across a distance of 100 ft (or 1–2 meters down per 100m distance). While grading the soil, remove rocks and other large objects that could interfere with the lawn's roots. Do not bury construction debris or other materials not naturally present in your lawn, as this could harm the lawn roots. A lawn needs at least 4–6 inches (10–15 centimeters) of high quality topsoil in order to grow and stay healthy. If your soil has a sandy or clay-like texture, use a shovel to thoroughly work in organic material to this depth. You may use compost, rotted manure, peat, or high-quality topsoil purchased at a garden supply store. Do not just place the new material over the old. This can create layers of soil that can be difficult for water or roots to penetrate. Some varieties of perennial rye can grow roots well over a foot long, which is why well-worked soil and annual aeration is so important. If you want detailed information on your soil, take soil samples and send them to a soil testing laboratory. The laboratory will conduct tests and tell you whether additional nutrients or pH-altering materials are recommended for your lawn.  If you are in the US, look for a Cooperative Extension office in your area. Most of these will provide soil testing services. If you do not have access to a soil-testing laboratory, you may find some information at home by testing your soil pH. Most larger retail nurseries carry home test kits. Most lawns prefer a soil pH of about 6.5–7. Starter fertilizer is high in phosphorus, which encourages root growth for new grass. Phosphorus is displayed using the middle number on the fertilizer package, so starter fertilizers are sometimes labeled 5-10-5 or 10-20-10. Always use the amount recommended on the fertilizer packaging, as too much fertilizer can kill plants. Do not till the fertilizer in deep; just rake it gently into the surface soil. If starter fertilizer is not available, use a balanced fertilizer (for instance, a 10-10-10 fertilizer). Assuming you needed to add in new soil or make significant grading adjustments, water in the new soil. For best results, let it settle for one week before planting. Grass will grow best when air pockets are removed from the soil, but not when the soil is too hard and compacted for roots and water to easily move through. Roll a light garden roller over the surface of the soil, filled no more than 1/3 of the way full of water. You may purchase strips of already-growing grass in the form of sod, called turf in some countries. This can take some effort to lay down, but will become usable soon after installation. Grass seed is much cheaper, but can take months to become a usable lawn, a constant fight with undesirable vegetation, and a year or two to become even and attractive. Grass seed is not recommended for significant slopes, as it can wash downhill during rain. Continue on to one of the sections below, depending on your choice. There are other, less common methods of installing a lawn. "Plugs" are small pieces of sod that are planted at intervals, then allowed to spread across bare soil. "Sprigs," also called "stolons," are stems of grasses that creep along the ground, such as Bermuda or Zoysia. These can be treated as seeds, but take care that the larger nodes on the sprigs are under the soil and watered regularly.

Summary:
Remove old plants with a hoe or machine. . Improve the soil (if necessary). Send in samples for a soil test (optional). Rake in starter fertilizer lightly. Water the soil and let it settle for one week. Roll the soil lightly. Decide which method of lawn planting to use.