The dreaded weeds
Keeping on top of weeds is essential, letting just one grow will result in a border full of weeds within a couple of weeks. If your starting out on a garden that's infested with weeds one of the best tips I can give you is to cover the offending area with an old carpet for six months. Preventing light getting to the weeds will kill them and their roots, in six months time you'll have a beautiful patch of soil ready for planting.
Lawn edges are on of those things that can make or break a gardens' appearance, you think that they are so small that they can't possibly make a difference, but the devil is in the detail. Keeping nice crisp edges can dramatically improve the appearance of your lawn. Every time you mow the lawn you will need to pay some attention to the edges. Perhaps even once a month - depending on your rainfall and soil type - you will need to re-cut the edges.
A few leaves on your lawn won't do any damage and will harmless rot in to the ground. If you're in an area where you have a lot of deciduous trees and you can't see your lawn for the leaves in the winter then you really want to think about collecting and removing those leaves. Wet autumn leaves get compressed and forms a barrier over your grass, this barrier will prevent air and light getting to your lawn and will eventually kill it. A lawn sweeper â especially the hand powered â type is particularly useful when it comes to collecting a large number of leaves.
Like fallen leaves, moss can do really bad damage to a lawn. It penetrates and smothers the ground at the base of the grass stems, slowly but surely it steals the ground from the grass and prevents it from growing back. Using a moss killer or preferable a rake and some hard work (it's more environmentally friendly and better for you) you can keep moss at bay.