Instructions
Head to Fuchsia City. You can reach it from Celadon City, Lavender Town, Vermilion City or the Seafoam Islands.
Go to far north side of Fuchsia City and enter the building set in the wall. The gatekeeper will charge you 500 coins to enter the Safari Zone. You will get 30 Safari Balls and 600 steps in the Safari Zone.
Move to a grassy place in the entrance area. You also can try a grassy spot to the right of the entrance area, but your chances of spotting a Pinsir are reduced. You will not find any Pinsirs above and to the left of the entrance area.
Change directions without moving. Every time you change direction you have a chance to spot a wild Pokemon. This allows you to hunt without using up your steps.
Throw a rock at the first Pinsir you see. The rock will anger the Pinsir and make it more likely to flee. If it stays, however, it will be easier to capture.
Throw a Safari Ball at the Pinsir to capture it. If the first Safari Ball does not work, throw another rock, followed by a Safari Ball. Repeat until the Pinsir flees or you capture it. If the Pinsir flees, keep changing directions until you spot another.
Save coins and buy a Pinsir at the house next to the Pokemon Center in Fuchsia if you do not have the patience to catch a Pinsir in the wild.