some aircraft are extremely docile and easy to fly. therefore they are very hard to get into a spin. honestly, with extremely light biplanes with nose-mounted engines that put the center of gravity far forward... it should be a little harder to get these old biplanes into a spin when compared to the more high-powered WW2 planes.
getting your plane to be tail-heavy and slowing down to stall speed is usually a good start. the Camel, Snipe, Airco DH2 and DH5. these could all get tail heavy more easily
to be honest, I haven't actually gotten into a spin yet... but I haven't been flying aircraft that were legendary for doing so. well, if I did get into a spin I usually recovered after just a couple of revolutions and didn't really think about it.
if you want to get into a spin I would suggest trying to flying in an Airco DH5. that negative stagger might be just what you're looking for. dive just a little bit to reach max speed, then zoom climb, cut your engine halfway through the zoom. as your speed starts to bleed off completely and you're just about to stall out THEN try to turn and level out at the top at the same time.
I say this, because in the past, the most common scenario where I got into a spin was typically trying to zoom climb into the blind spot of a two-seater with an under-powered plane. I will realize that my closing speed is faster than I originally wanted, cut the engine to prevent a collision, start shooting him up, and then realize I have to disengage.
so... try that for getting INTO spin. as for getting out... eh, I don't remember how to explain that!
I haven't flown enough WOFF to reallly test this theory - but back in RB3D this was a pretty good way of getting myself to spin into the ground at low altitude.