What are the best ways (and things to avoid) to crosstrain?

[fatgrosshog]

I didn't start rowing until later in life, so unfortunately I haven't been on a formal training program for rowing the way that I have for other sports. When I was a swimmer, our coach told us to lift light weights with high reps, and he said that if we go heavy weight with low reps, it would make us slower rather than faster swimmers. When I was a football player, we did lots of sprints, and our coach told us not to do much distance running because it would recruit slow twitch muscle fibers and thus make us slower on the football field. In rowing, what are the main factors that should be avoided or focused on to max out our times?

[ArmandoChavezUNC]

I don't know much about cross-training but from some rowing literature I've read (specifically Volkner Nolte's Rowing Faster) it seems as though running isn't the best for XT when rowing. Bicycling and skiing are pretty popular though.