Ask for the menu, which will include a variety of cannabis buds and hash, ranging in quality from OK to incredible. Feel free to ask questions, the staff are typically quite friendly. You may also want to ask if they have a pipe or bong to use. Rolling papers and filter tips are available as well. For you Americans that have no idea what a gram is, a dime bag is typically about half a gram.
Some places offer pre-rolled joints of pure grass or grass and hash joints mixed with tobacco.
You are allowed to bring grass from one coffeeshop to another, just be sure to purchase something to drink. Just don't be blatant about it. Coffeeshops also offer space-cakes. These are cookies or brownies with hash or bud in them. Be patient, and don't go crazy.