Spacing is important to make full and effective use of your reach but it also depends upon what arm is your main weapon. You would want your opponent to be nearest to where that strong arm is to put it to bear upon the adversary. Whether you are right hander or orthodox or left hander or unorthodox or southpaw fighter, you would want to place your foe within the most effective striking distance and keep him there. Of course it will also depend upon your favored mode of fighting whether you are a boxer, boxer/counter-puncher, boxer-puncher and established strongest punch whether it's the jab, the hook, the crosses, the uppercut or combination of those.
You really need a good trainer/coach to help you out on this.
keep your distance and don't initiate the action. People with less reach will try to get in close where they can be effective and they have the advantage. Jab to keep them at a distance and move in and out quickly. shorter people will try to get you to throw so they can find an opening and move in close. You can also stiff arm shorter people to keep them away. also, when they throw a punch you can block and throw back at the same time. your punch will hit them first and even with their arm extended they wont be able to reach you.
Simple. Keep them at a distance. Your advantage comes from the range where you can strike, but the other guy can't. The more the other guy is in this range, the more you can use this to your advantage. The challenge is making sure the other guy stays in the distance.
you have to use the jab to keep the rival off balance and at distance, so practice in the gym the jab, prefer With a boxing sparring partner
Obviously I've a wrestler first and I've been able to use my long arms and legs to hit throws, trips, takedowns and slams on short people in wrestling, but what can I do in boxing to keep guys at a distance. I've had only one amateur fight about 2 years ago against someone who was really short and I was able to win but I couldn't use my length to an advantage.
Stats just incase
Height: 5'7 1/2 - 5'8
Reach 73 inches
I'm extremely quick and have good foot work and pretty strong.