Mowing the lawn isn't as simple as pushing the mower back and forth. There are a few issues that can occur if you don't use the right techniques.
Flat grass is grass that seems to grow almost as if it is laying down in one direction. Grass can flatten out because it is too long, but if it looks flat after mowing then the problem is likely with your mowing pattern.
Following the same path every time you mow trains the grass to lean in that direction. You can solve the problem by varying your mowing pattern every time. One week use a horizontal path, and the next week do a vertical path. Follow this with diagonal mowing paths.
Scalped or bald areas are usually the result of dips and hollows in the yard. As the lawnmower comes out of a dip, it cuts the grass too low on the upward slope. These dips and raised areas can be the result of the soil settling, such as from tree roots decomposing beneath the lawn, or it can be from ruts in the lawn formed from foot traffic and repetitive mowing patterns.
A short-term fix is to lift the lawnmower blade by 1/2 to 1 inch and simply leave the grass a bit longer in the dips so that the raised areas aren't scalped. For a long-term solution, fill in the low areas with a mix of compost and sand until just the tips of the grass are showing. Allow this to settle for a few weeks, which allows the grass to root in the compost mix, then repeat every few weeks until the lawn is level.
Yellow-brown tips on the grass are common in spring when the grass first begins to grow, but the first mow should get rid of them. They can be a result of nutrient deficiencies later in the season, but more often your lawnmower is to blame. Dull blades don't cleanly cut the grass but instead tear and crush it. The result is the discolored tips.
Your lawnmower blade needs to be sharpened professionally at least once a year, in spring before the first mow. Then, it should be rinsed off after every mowing session so that wet grass doesn't rust or dull the blade. To truly ensure a sharp blade, continue to sharpen it every month or two for the duration of the mowing season.
Contact a lawn mowing service for more help in combating common lawn maintenance issues.