If you've found yourself enjoying a new author and want to find the rest of the titles in the series, try What's Next. This database comes from Kent District Library in Michigan and is quite handy at generating lists of series titles--in order.
The search box is straightforward. Put in a title, author, or series. You can specify reading level or genre, but generally doing a simple search will be enough to get you your list. Results are shown by author, then series. Keep clicking the plus sign until you get the list of titles. Clicking a book title brings you to the Kent District Library catalog so you don't need to go that far; just write down the titles or copy them to a file so you can search your own library's catalog or browse your favorite bookstore's shelves.
Another useful website is Fantastic Fiction. It's based in England so you can find UK information for many books and authors (like series titles and book covers that might be different from one side of the Atlantic to the other), but there's also tons of US info as well. You can search or browse the site directly, but you might also come across it when searching Google as it gets high rankings in Google's algorithm. Fantastic Fiction includes some brief descriptions as well as lists.
Google itself is a good place to start your series search. Most authors have their own websites, although there are still a few who rely on their publishers for their web presence, and you can usually easily find lists of titles and series order. Search either for the author's name or the series name, or perhaps some combination of both.
If you have a library card, check with your local library and see if they subscribe to NoveList. This is a great resource for finding books for all ages. You can search by title, author, subject, series, or keyword ("Describe a Plot"). Once you find a book you like, you can ask NoveList to show you similar books by checking off descriptors that you definitely want included and ones that probably want included. Book reviews are available. Also available are author-readalikes, awards lists, and suggested reading. You can even create an account for yourself and build your own lists.
The capability exists to search your library's catalog directly from NoveList, but not all library systems have enabled this feature. Check with your local librarian for more information.
Fiction Connection. You can see what it looks like, but in order to actually find anything you'll need a library card from a participating library. Once inside, you can search or browse. You can find similar titles to ones you like or broaden your reading experience by looking for books you might not normally pick up. Book reviews are included.
With all these options, you never have an excuse that you have nothing to read.