Advice!

My husband has finally agreed to go vegan! (Cowspiracy tipped him over the edge!) I was vegan once before but I got really sick and was one of those people who assumed it's because vegan 'isn't healthy after all' I know now it's not true and I have bought cookbooks to get recipes from that are nutritional. Anyway my question is what is the one thing you wish you knew when you started your vegan journey? Your secret to success? Any tips you can give? We are going shopping on Saturday (when our local farmers market is on) so would love some tips :)