Do these things to protect your trees

If you have not yet cleared out fallen leaves and other debris from under trees, definitely do that. Yes, they can serve as “mulch,” but they’re more likely to carry insect eggs and/or fungus spores that will cause problems next spring if not now.
Bring in new true mulch This is a must for ensuring whatever rain we do get soaks into the soil rather than running off. Mulch conserves existing moisture and can also keep roots warmer. An inch is the minimum advised thickness, but three inches will provide much better protection, including discouraging weeds from growing. And, by the way, confiders need mulch as much as deciduous trees.
If you have problems with mice outdoors, leave a small space between the mulch and tree trunk, and check it periodically over the winter. Mice can chew all the way around the base of some trees, which will be fatal (for the trees, though unfortunately not for the mice). Rabbits? You’ll need to use paint-on repellent or wire mesh wrap.
Pruning keeps trees shapely, prevents disease from spreading and encourages healthy new growth. Remove any damaged twigs or branches. If necessary, remove inward-growing branches to allow more sunlight to reach the interior. Careful pruning can also lighten the load on branches, making them less vulnerable to winter breakage.
Young trees require special attention. In fact, if your trees are very young, you could consider covering them over the winter until they’re older and stronger. Or you might want to wrap their trunks, the equivalent of wearing a coat.