Until the weather is warm enough, and the ground dries out enough to work, the first tasks in the spring would be cleanup and pest prevention.
Now is the time to trim back and remove all the dead debris from your perennials, if you have tall ornamental grasses, you can cut them back to an inch above ground level, cut your hardy hibiscus stems down to about an inch as well. I suggest leaving an inch exposed so you can identify where things are when you start adding new plants.
If you are like me you would have distributed some of your fall leaves to add a layer of insulation over perennial and bulb beds, as well as your vegetable garden if you grow perennial herbs, at this point I would rake them up and compost them, it is also best to remove or rake to the borders, any wood chip, or shredded decorative mulch used last season, exposing the dark earth to the spring sun will warm the ground, and help dry it out, much quicker than if this insulting layer were left in place. Do not replace mulch until ground temperatures reach the 60's, or the nights stay above 50 for over a week. The ground will warm to a higher temperature faster than the air will.
If you didn't prune last fall, now is the time to cultivate how your trees and shrubs will grow this season. When pruning back trees and shrubs, remove the branches that extend past the general width of the tree or shrub, this is where the feeder roots tend to end, keeping a balance of foliar growth and root mass, will reduce stress and increase drought tolerance. Follow a branch that is to be removed, observing the nodes on bark, and cut just past the node facing the direction you want the new branch to grow. Do this every year and you will have a beautiful shape to your trees and shrubs. If you have young trees, or fruit trees remove all branches from the bottom 1/3 of the trunk, these will be considered sucker stems and will rob the fruit bearing branches from energy to develop more, larger fruits. When pruning like this, brush the exposed cuts with pruning tar, or tree paste, to prevent pest and disease infiltration. At this point it is a good idea to spray your fruit trees with dormant fruit tree spray, this will keep your apple, cherry, peach, apricot, and many others fruits from becoming infested with parasitic bugs and blossom fungus.
If you do not have fruit or foliar trees and plan to put some in, it is best to get them into the ground before they start to break their buds. Many people wait to buy these so they can see it is actually alive before planting it, thinking they will save some time and effort should a dormant they pick not be viable, but nothing is further from the truth. Most nurseries have 1 year guarantees on trees, if you choose a dormant that has no dessication on the branch tips, and have hard packed, tightly closed buds, the chances of survival is much greater than planting after the bud have broken, and the tree begins to leaf out. The reason for this is simple, a tree that is transplanted a month or two before it is to leaf out, will have the chance for the root system to recover from, either being balled and wrapped, or root bound in a pot and then transplanted, and even when transplanting dormant trees and shrubs, it is best to water initially with a water soluble fertilizer like miracle gro, to prevent root shock.
In order to insure a successful transplant there are certain rules of thumb to follow. Always dig your planting holes two times as wide and two times as deep, as the root ball or pot, the plant came in. Take half the dirt you removed and add it to your compost layers. Replace the dirt you removed with your own compost, or a 2-1 ratio of soil to bagged compost or manure, then add 25% peat moss, mix and use to back fill the hole after orienting your new tree or shrub, how you want it to stand, if this is an evergreen you can mix coffee grinds, or pine needles into it to acidify the planting medium, if these are not available then increase the peat moss to 40%, this will also help acidify the soil.
Feel free to ask questions!