DEVONthink is very useful to store research articles, web bookmarks and other documents. The excellent search, ‘see also and classify’ and smart rules (for filing etc.) can save you a tonne of time in terms of organisation and retrieval. (I don’t bother with a separate reference manager any more for storage of journal PDFs as they are not as good as DT for reading, annotating, searching and discovery).
I would also recommend learning the basics of Markdown and perhaps a personal knowledge management system such as Zettelkasten. DEVONthink is a great citizen for both. This may require an upfront investment in your time but it pays back in spades. You will soon find you can quickly capture and link your ideas. The ability to link your notes to your other resources using Markdown and to return to the previous note/ document from within the document viewer is an efficient way to navigate too. If you already have a preferred PKM, DT is more than likely flexible enough to accommodate that as well.
Lastly I would say to just start using the application and develop a system that suits your needs over time rather than try to start with a Taj Mahal of a process. Your use will evolve as you recognise your needs and you can evaluate the relative value of each feature with a bit of investigation and practice. When you’re ready for to explore further the tips and tricks section (Ellipsis button “…” button at the top of the left-hand-side panel) is a useful resource.