You should mow your lawn as often as required, rake out as much debris and dead moss as possible. Remember to apply a lawn treatment to feed and weed too. If applying moss killer at this time remember and scarify out the dead moss later.
Keep on top of the weeding in the garden, 20 minutes weeding when required could save you a back breaking catch up session in a couple of weeks!
Tie in any climbers and support any long herbaceous stems, this will help the plant give you its best show. Early flowering shrubs can be pruned back now, such as Kerria japonica, Ribes and Forsythia.
Any topiary could have a light clipping at this time.
If not done already please please please remember to feed your garden. This is not only pots and containers but your whole garden. A good layer of farmyard manure, which can be purchased from the garden centre in bags, will help to improve the soil condition. A slow release fertiliser such as Osmacote will add nutrients that the soil may be lacking.
We can still be susceptible to frost, so we must be careful, but now is the time to be planting up some summer baskets and containers. Use moisture retaining compost and slow release fertiliser to ensure longevity in your plants during the hot weather. These can be grown ahead of time if you wish and grown on in a greenhouse, ready and full to go outside. If there is a chance of frost then take them in to a conservatory or greenhouse to protect them at night. By putting them out during the day you will help to harden off the plants for summer.
The bugs and slugs are on the go and now is as good a time as any to start keeping on top of them. Some choose to use chemicals when spraying or the alternative of organic sprays is better for the environment. Keep a note of the dates you spray, you could make up a calendar for future spraying. For slugs beer traps, slug pellets, broken eggshells are just a few ideas but hand picking in the evening is another option!
Apparently making your own garlic spray is a great idea, the slugs hate it. Boil up some cloves of garlic and then use that water, diluted, to spray round the garden. I have seen this work really well on a garden full of hostas!