Many print the plans out full size using acrobat, tile using acrobat if necessary.
When you have the plans printed, (and joined into a single sheet if required), you can adhere or clamp the plans to the FB and use a pin to poke through all corners and curves. When done remove the plans and play "Join the Dots" with a pen and ruler. It is now ready for cutting.
Others often adhere the plans to the FB and just cut out directly through the plans into the FB.
or the better/easier way... is do the first step but do it with card stock... it's not as firm/stiff as the poster board but still easy enough to use... I've done both... I do it all with the card stock now as it saves a step... from there I pin down the plans onto foam board, I picked up a cork board that is large enough for a single sheet, I trace out the plans, for score cuts I just prick the surface so it doesn't poke all the way through and just leave a mark to score with the blade... for lines like the servo cut outs and such I poke a hole at either end, when I pull off the templete I put a light line/mark