I think Nixon shouldn't have made his pledge to campaign in fifty states, since that led to him having to campaign in states he had no chance of winning or states that wouldn't matter.
Agreed.
Also, Nixon should've done a radio-only debate. Those who listened to it on the radio thought Nixon won, but those who watched it on TV thought JFK won.
Agreed.
If Nixon had to do a TV debate, he should have shaved and worn some makeup. Also, he should have not injured his leg on the campaign trail (or at the very least, he should have taken a break from campaigning right after he came out of the hospital), since this led to him looking uncomfortable and sickly during the debate.
Also, I think that Nixon should have spent more time in swing states like Illinois, Missouri, Texas, and New Jersey, since those were close states within his reach. Had he not made the 50 states pledge he probably would have won them, or at the very least, he would have stood a greater shot. Had he carried all of those states, he would have won (but he would have won with just Illinois and Texas or Illinois, New Jersey, and Missouri).