We crossed the border into Canada for the first time earlier this year and, before doing so, read as much as possible on the official websites (as well as RV forums) about what was allowed / prohibited. As a result, we had a thorough clear out of cupboards, refrigerator, drinks cabinet (that was particularly enjoyable apart from the knowledge that we'd have to restock!), etc and even washed the underside of the RV and jeep to remove any dirt thicker than a layer of dust. We also made a list of all remaining food items that we understood were ok to take across but had to be declared and prescribed medications.
Anyway, our crossing north at Carway took less than five minutes (including queuing and a few questions) and, after a wonderful three-weeks roadtrip across western Canada, the return crossing at Peace Arch, Vancouver was similarly uneventful (although the queuing time was somewhat longer).
I guess the motto is be prepared for the 'worst' (secondary questioning / search) and be pleasantly grateful at anything less.
