Feed new colonies and monitor your existing ones. Spring can be a time of long draw-out rainy spells (this year in particular). Make sure all colonies have ample access to sugar or honey stores. A pollen patty isn’t a bad idea either. If medicating, all medication should be off well in advance of putting on any honey supers.
Start checking for indications of swarming, including: back-filling brood cells with honey, overcrowding, and swarm cells. If spring re-queening is your plan, do it during a good spring flow.
Nectar sources: Maple, dandelion, clover, raspberry, native blackberry.
Pollen: Late-blooming fruit varieties, dandelion, scotts broom, blackberry.