Prepare to Solder
Be Confident
Make sure you checked the prerequisites we covered earlier (reference designators, component values, etc)
Make sure you're confident in your soldering. It's so important that it's worth repeating. Bad solder joints are one of the most common reasons first time pedal builders run into trouble.
Revisit the How To Solder book if needed, or try more practice kits for half-off if you're not completely confident. If in doubt, post some pics of your practice board to the support forum.
Set Up Your Work Space
Separate PCBs
Your pedal will use three (3) printed circuit boards (PCBs). They are manufactured as one unit, so the first thing you need to do is snap them apart.
You can use your hands to break them apart at the perforations. The two little tabs will probably still be attached. You do not need to remove them, but it will look nicer if you do. Line up your flush cutters with the perforations, apply firm pressure by squeezing the handles, and turn sideways to snap the tab off.
Breaking is easier and safer than trying to cut the PCB.
Snap, don't cut.
Anecdotal Warning
WEAR SAFETY GLASSES
I once cut a perforated PCB apart with flush cutters and its blade snapped. A sharp, metal, triangle projectile hit my face within an inch of my eye and could have blinded me if not for glasses and luck.