Oh I am so happy you got one. They are great. I would highly recommend getting some canisters. That is what I used for lettuce so it doesn't smoosh it
Here are a couple of tricks to keeping the juices from flowing. I have the Tillia food saver so I am not sure if the Black and Decker lets you do this, but make your bags extra long if you can. That helps to keep the juices from going into the machine as much. The other trick is to take a paper towel and fold it up and put it in the bag at the top before you seal it. This way any juices that do make it up that far will be absorbed by the paper towel. Have fun with your new toy. You are going to love it!
Oh Kitchenelf, on my foodsaver there is a little reservoir that any juices that come out go into. You can then just take a paper towel and clean it out very easily. I have never had a problem keeping mine clean and gunk free.