Fish feed all year long, hence ice fishing. They will move into the shallows all year to feed. They don't do it as frequently in the winter but they do still move to feed. I always set a trap when ice fishing leading into the shallows and catch fish on that trap besides the ones in deeper holes.
I have caught fish in RI right after ice out. Just make sure you pick a body of water that isn't stocked by the state for trout. They all close March 1st until the 2nd Saturday in April for all fishing.
Activity does increase with warming water temps but they are still active enough to catch them when the water is cold. In the past when I had more time I would always take my canoe out in March and target bass and sunfish and usually did pretty well once I found a pocket of fish. A sunny day around mid afternoon when the water is at its warmest for the day always seemed best. Some days all it takes is for the water to warm a degree or two to turn the fish "ON". I would look for places that ice out first such as the Northern coves, they usually have the best southern sun exposure and heat up the fastest. Also a place where there is some current moving in or out of a pond with shallow water nearby is a good hot spot for early fish seeing as it is free of ice sooner.
In terms of flies nothing particularly special other than something that looks buggy with lots of built in movement. Small nymphs and streamers for gills and small bass and crappy. Bigger streamers for bigger bass. If you are fishing from a boat a sinking line may be something good to invest in this time of year, but a floater works too so don't completely avoid it. Don't be afraid to vary your presentations. Slow is the normal rule of thumb but fish will hit a fast presentation in cold water with the right trigger.
Your hooks sharp????