Precision craft knife (X-Acto style), a metal ruler for straight scores, and tweezers for small parts like the landing gear.
The quality of your final model depends 90% on the quality of your initial template. Unfortunately, many free templates online are low-resolution or mathematically "off" (resulting in a fuselage that looks like a squashed tube). Here is where to look for designs: boeing 737 200 papercraft
If your template includes the long metal ski under the nose, cut this from or color it with a silver Sharpie. It attaches between the nose gear doors. Precision craft knife (X-Acto style), a metal ruler
For scale modelers, the 737-200 represents the bridge between the analog jet age and the digital future. It flew for airlines like Lufthansa, United, Piedmont, and even the legendary Canadian North (with gravel kits). Here is where to look for designs: If