There is a number of accessories you can try to take your crossbow shooting to the next level. However, the most essential ones include shooting stick, hunting backpack, GPS, cocking device, crossbow sling, crossbow quiver, crossbow broadheads, crossbow holder/stand, crossbow target, field points, and crossbow case. A shooting stick will help you stabilize the bow either kneeling or standing to get the perfect shot every time.
A good hunting backpack will provide you space for keeping water, snacks, knife, GPS, or anything else you might consider necessary. Some pros also suggest applying some lube and wax to the string after every ten shots to keep things going smoothly and effortlessly.