1. Boss OS-2 Overdrive
2. Distortion pedal
3. Crybaby Wah
4. EQ pedal
Here's why:
The OS-2 Overdrive should come first in the chain because it's a "clean" overdrive that adds a bit of warmth and saturation to your tone. It's best to use the OS-2 before any distortion pedals, as this will help to preserve the clarity of your tone.
Next in the chain should be your distortion pedal. Distortion pedals add a more aggressive, overdriven sound to your guitar tone. Placing the distortion pedal after the OS-2 will help to ensure that the distortion doesn't become too muddy.
After the distortion pedal, you should place the Crybaby Wah. Wah pedals allow you to add a "wah-wah" effect to your guitar tone by sweeping the pedal back and forth. Placing the wah pedal after the distortion pedal will allow you to control the amount of distortion that's applied to the wah effect.
Finally, you should place the EQ pedal last in the chain. EQ pedals allow you to adjust the frequency response of your guitar tone, which can be helpful for fine-tuning your sound. Placing the EQ pedal last in the chain will allow you to make sure that the overall sound of your guitar is balanced and clear.