Here's a tip: You can search for a list (they're in a category called Listopias) of writers or whatever that you have many works of. Then you can just scroll down the page and click the 'add this to my library' hover menu (or clicking on the 5-star bar labelled 'my rating' does the same) without needing to open separate pages or run separate searches for each one. Tagging is a bit of a hassle b/c you can't tag multiple items at once, but if you go to your My Books page, set the 'display' to a large number, and then scroll down to the first untagged book (at the bottom), when you type in the tag you want to add and hit 'enter' to select it, it reduces the drop-down list so only that tag is displayed. Then you can just click on the 'tag' link of the next entry above it that you want to add the same tag to, and the popup should move up without needing to close and re-open, with the right tag pre-selected. This saves a lot of time because the whole process to tag one book is reduced to 1. Click on 'tag' and 2. Hit enter.

It doesn't work going from top to bottom in my browser because the tagging popup appears underneath the add-tags link, and it obscures the next link down in the list.