If your lawn is relatively flat and not huge, chances are you'll be perfectly happy with a push mower—that is, a mower that's not self-propelled. In addition to being cheaper, mowers without power to the wheels are lighter, have fewer mechanical parts to wear out, and are usually easier to maneuver. If you have hills or a large yard, a self-propelled mower is a better choice. Front wheel drive mowers pull the mower along but may lose traction on hills, where you tend to push down on the handle. And if you bag your grass, the weight of the bag will reduce the traction on the front wheels, making the drive wheels less effective. In most cases, rear- wheel drive is the best option since it works great on hills and with a bag. All-wheel drive is needed only for severely sloping terrain. If you buy a self-propelled mower, consider upgrading to variable speed for more flexibility in matching your mowing speed to the lawn conditions and your walking speed.