If you are itching to get out and do yardwork this week-end, go for it but don't go crazy! It is still early days and we want to keep our plants well-insulated for quite a while longer. This means don't be removing any winter mulch just yet, and definitely don't be walking around on muddy garden soil, which will destroy soil structure. (Actually, some people recommend not even walking around on the lawn when it's soggy but if you know me, you know I don't care much about lawns!)
If you haven't pruned your shrubs yet, that is certainly something you could get done this week-end. Don't prune spring-blooming shrubs like lilacs (you'll cut the flower buds off!) and wait to prune shrub roses until late May or even early June as their tips usually die back and it's easier to see what wood is alive/dead once things are leafing out. Here is a recent post of mine on pruning, with lots of links to extra resources.
If you're starting to cut back your perennials left standing for the winter, just remember not to tramp around on your garden soil. This year, I am trying composting in place. Which means I will be chopping up my leftover perennials into little bits and leaving them in place on the ground. This makes free mulch! It will look a little messy in early spring but the plants will soon grow to cover the old stuff. As my garden gets bigger and bigger I have realized I need to use as many low-maintenance gardening techniques as possible. Why tote all the dead material over to the compost bin, turn it over all summer (which I never get around to doing anyway) and then when it has sufficiently decomposed, dig it out and spread it back over the garden? Life is too short. (Besides, to be honest, I never got around to emptying my compost bins last fall so there is nowhere to put all the dead plant material this spring.)