Do these three jobs now, for an instant effect that will keep for months.
1. Clear out weeds and spent annuals
And, if you are feeling tidy-minded, cut the dead stems of herbaceous perennials just above ground level. You could leave them on to provide some seed and shelter for your garden's wildlife. Either way, plan to spread a layer of mulch (compost or leafmold) over the soil before any spring flowers emerging from the ground make the job too fiddly.
2. Neaten up lawn edges
Now the ground is soft, it's easy to create a crisp lawn edge using a sharp spade or a half-moon cutter. Aim for either a straight line (don't do it by eye, let a taut piece of string guide you) or a gently flowing broad curve. In my experience, this one thing improves the look of a garden like no other!
3. Plant up winter pots
Something to put by the front door, to cheer you up when you come home, with a few more in the garden, placed where you can see them looking out of the windows.
Use frost-proof containers, just in case. Larger ones, with more plants, will have more impact.
There are the evergreen stalwarts, some with long-lasting berries or variegated leaves, like skimmia, euonymus and ivy. Different shapes and leaf colours will come from hardy ferns, Heuchera, Carex sedge, ornamental cabbage or kale (yes, the trendy super-food!).
Finally, for some jolly bright colours, there is primula and polyanthus, winter-flowering pansies and violas. Daisies, forget-me-nots and wallflowers planted now will join the flowering chorus later, together with daffodils and tulips.