In no particular order....

1) You have to make a lot of stuff so you can make airplane stuff. From building work benches to jigs or other tooling... be prepared to spend hours doing something other than making an airplane part.
2) It would be helpful to have someone who can read plans that can double check layouts or dimensions for critical cuts...like those hinge slots... simple mistake and I checked, re-checked, and checked again on my own, but still got it wrong. Kind of like needing an editor when writing. Unfortunately, there aren't very many active builders in my area... even the local EAA chapter has only 3 active builders. In addition, EAA doesn't have a single tech counselor listed for wooden plane builders in the state of Washington.
3) Some very basic power tools make all the difference in the world. Though I would love to have a state of the art workshop with top of the line tools, the simple truth is that I don't have the space or the budget right now. But a $139 Wen belt sander has been an unbelievable productivity booster. After realizing I have 550 3/4" wide gussets to cut to shape and cutting enough for patterns and one rib side (I've been using a utility knife and/or dremel tool with a tiny saw blade on it), it's time to buy an inexpensive table top band saw... I've cut about 60 of the gussets using the utility knife/dremel now and it's a pain!
4) Where a dust mask EVERY time you turn on the sander--I got a little lazy and it's taken me about a month of coughing to give the Simpson DOH! slap to my head on this.