One of the secrets of great manual sex is varying your hand motions. He will notice the difference. Don't get into a routine where the strokes are dull, and noncommittal. Give it to him good. Bring both well-lubricated hands down on his shaft.
Some cocks are so big they require both hands.
If your partner's doesn't, then use the other hand to caress and lightly flutter his balls, or tighten around the base of his shaft. If both hands fit along the length of the shaft, move then together, up and down, in the typical pumping motion. Pretend you're holding a baseball bat and are about to score a grand slam. You can also vary the directions of your hands, one up, one down at the same time. There's no doubt that two hands are better than one.