Now is a great time to check your Japanese Acers. These plants do not need pruning, but they do always get little bits of die-back. Once the leaves have dropped and the plant is dormant, cut out any dead stems to just above a bud. You can also cut back anywhere you need to improve the shape of the plant.
It is also a good idea to cut the grass away from the trunks of any trees, particularly young trees that are growing in your lawn. If you let the grass grow right up to the tree it will compete for nutrients and water. You also risk damaging the tree when trimming the grass. Once the grass is removed, mulch the bare soil.
It is also time to check your tree supports. Make sure that the ties are still supporting the trees, but have not become too tight. Loosen or replace as necessary. Check too that the stake is still in good condition and has not rotted at the base. If it has, replace or if the tree no longer needs support, remove it.