Above all else, make sure you take it slow. Your partner may have longed for a big cock but it's unlikely they've ever experienced a big cock in it's full glory. Make sure to work in every last inch to ensure that they don't miss a single centimeter of pleasure. A great technique is to thrust it all the way in, then use your hips to make circular motions, grinding the shaft all around. You'll be probing away at full depth, a sensation most women crave deeply.