There are several methods for aiming the arrow when shooting a bow. The method depends on the type of equipment being used. Three types are discussed here - primitive, traditional and compound.
Most primitive archers use the instinctive method of aiming. The process is similar to shooting foul shots in basketball. The archer looks at the target and aligns the bow instinctively and releases the arrow. At first, the method may seem very inconsistent, but as skill level and practice evolves, accuracy will improve significantly. The human brain is a remarkable computer and is able to record the experience of practice and refine the skills needed to hold the bow unconsciously in the correct position to achieve results. Instinctive shooting is very fast and primitive equipment is light and fun to shoot.
Primitive bows can be longbows or recurves, but use no sights or stabilizers. Many of them are handmade. Primitive selfbows are made of one piece of wood as opposed to being laminates.
Some primitive archers use the "gap" method. This involves consciously looking at the tip of the arrow and the target and determining the necessary "gap" needed to direct an arrow to the target. This method is slower and requires more conscious effort to be successful.
Traditional archery is similar to primitive and they actually overlap in some cases. Traditional bows can be longbow or recurves and some use sights to achieve consistent success in hitting targets. Some traditional bows that are used in competition may have stabilizers and sights. They are a step up the evolutionary ladder from primitive bows.
Compound bows are the next step up the ladder. They are constructed from cast metals, laminates, fiberglass or various combinations of these. They use cables, pulleys and cams to achieve "let-off" of draw weight at full draw. This allows reduction of 65% to 80% reduction in the weight that the archer has to hold at full draw. Almost all archers using compound bows use sights.
There are a number of sights that use pins that use light gathering fiber optics to assist in sighting. The various pins are adjusted so that each one is set for a known distance. The archer either estimates the distance to the target or uses a rangefinder to determine the distance. Then he selects the correct pin pre-set for that distance.
Pendulum sights are often used from treestands to compensate for shooting at a downward angle. Shooters should always bend at the waist when shooting from an elevated position to maintain correct anchor point.
Regardless of the type of equipment, archery demands more practice to maintain accuracy than shooting a gun. The muscles that draw the bow must be maintained by frequent use and practice keeps target acquisition sharp in the shooter's mind.
Shooting with sights is easier to maintain once the archer knows the basics. Instinctive shooting requires more frequent practice to keep the sight picture fresh in the mind.