I like to use my middle pin as my reference. When I am sighting in I want to be deadly accurate with the middle pin before moving on to my others.
Some archery hunters show up for a big hunt with a bow that is not properly sighted-in. I watch them working at the practice bale, only to become demoralized on the eve of the hunt. Their bow isn't shooting well and they panic. They don't trust their set-up and immediately begin moving sight pins. Soon they have a mess on their hands and their whole hunt is in serious jeopardy.
It is far better to approach each hunt with total confidence, knowing that your bow is perfectly sighted-in. You will trust your rig when things go a little south in practice and focus on yourself as a potential cause of loss of accuracy rather than blaming equipment.
My bow gets really beat up by the end of a long season. Yet, I am confident that the sight, nock point and rest will be where I need them when the shot finally comes.
When choosing accessories select only very rugged gear with solid locking systems and the very best string and harness system you can afford. If the gear feels the least bit flimsy, get rid of it fast. Rock solid accessories, held in place with Loc-Tite, will not move unless you run over them with a truck. When you have gear this tough, you won't be as quick to blame the bow after a few wild arrows.
It is easy to shoot left or right if you cant (lean) the bow while aiming. On level ground at the range, you may become good at holding the bow straight up and down without an aid, but in hunting camp on sloping ground, or when leaning out to make a shot, you are very likely to cant your bow. A bubble level will eliminate this source of human error making you more confident in your sight settings.
Set Your Middle Pin
Move your top pin to the top of the sight body and then space the other pins appropriately. Stand ten yards from the bale and use your top pin; move the sight body up, down, left or right until you are hitting roughly where you are aiming. Now, move back to the distance of your middle pin and spend the next several days fine-tuning that setting. Focus on using the very best shooting form you can muster. I use my middle pin as my reference. It is the pin I am most likely to use on an animal and it is the pin I use when I can only shoot an arrow or two for practice.
At first, don't even worry about your other pins; get that middle pin driving tacks. If it takes a week of daily shooting, so be it. You need to know you are deadly accurate with that middle pin while using correct form before moving on.
Your form changes from time to time. It is important to sight-in over a period of days being very conscious of your technique. When you start to shoot poorly later, you know to look to your form rather than questioning your bow.
Set The Other Pins
It should take very little time to get the other pins set after nailing down your middle pin. You only have slight vertical adjustments to make. After setting up a few bows, you will get so familiar with your arrow trajectory that you can come very close to positioning these other pins before you even shoot.
During each practice session, be sure to spend some time practicing at each distance. While I may spend most of my time practicing at long range, I always take a few shots at each distance (and at distances that force me to gap between pins) so I remain confident at each.
Monitor Your Bow
If you know your pins are set perfectly, don't move them if you are shooting poorly unless you can prove the bow has changed. This brings up a key part of this column, the ability to monitor your bow quickly and precisely so you can tell when something changes.
When you have the bow perfectly sighted-in and shooting great, take several measurements. First, measure and record the exact position of the nocking point relative to the bottom of your arrow rest groove (or the cushion plunger hole if you are shooting a fall away rest). You will need a T-Square to do this properly. Next, measure and record the distance from your nocking point to your peep sight.
With the arrow resting properly, measure and record the distance from the front of the rest shelf to the bottom of the arrow. Next, do the same from the side of the sight window to the side of the arrow. You can also take a few measurements of your sight, but short of a bent pin, or loosened bolts I have not seen any sight body failures when using sights of rugged construction.
If you spend the time to make sure that your bow is deadly accurate and then log all the measurements, you will know quickly when poor shooting is the result of poor form or the result of changes within the bow. You will feel like a pro. This is the way to greater consistency on the range and greater confidence in the field.