You've gone through the effort of putting your collection in RocKeeper (either by entering them one at a time or by letting us help you), but you want to start taking advantage of the advanced search features.
Some are pretty intuitive.
If I search for fluorite, it will return all my fluorite specimens (sorted by collection number).
If I search for 2003, it will return in my collection from 2003.
RocKeeper is also aware of mineral groups, so a search for tourmaline will return all my specimens with minerals from the tourmaline group (for example, my elbaites and uvites).
If you've taken the time to put in the sizes of your specimens, you can take advantage of the assigned sizes. One thing I like to do is make sure I have perky box labels for my minerals that are thumbnail size. I can do a search for thumbnail, or simply t as a shorthand, and it will show all my thumbnail minerals! Then I can click on the "Labels" section, select the "Perky Box Labels", and press the "Create Labels" button to get a PDF with all my labels ready to print!