Soft pencils (B or 2B) and a marking knife, and a wheel gauge.
Before I bought a Pfeil I used one of my penknives. It sounds silly, but you need to know where it will cut (it's not a good idea to dig into the edge of a rule or square). The Pfeil is either-handed (useful) and quite easy to keep honed (important).
Soft pencils don't mark the wood as much - if you're marking with a pencil it's either because you want it clearer or you want to erase the mark later. HBs are just about OK, but anything harder leaves a dent in softwood. I do use a sharpener, but I learned to sharpen fast with a single sided razor blade years ago, and so prefer to sharpen with a knife if one is handy (not the Pfeil!). You can make a thin wedge-shaped tip which is stronger than a sharp point.
Also useful: cheap permanent pens from Asda in black blue and red - they write on plastic and various sticky tapes well. Chinagraph pencils (old habit from tape editing) they're not cheap but come in bright colours including white and yellow, and work well on smooth surfaces. Handy for the router table, but the colour rubs off easily, and they don't sharpen to a point. Remove with alcohol.
