Firs, I'll say that there is no requirement to have read the previous ones to get enjoyment of the series.
That Said, having read those, does add a lot of depth as you can see a lot of the self referencing and in jokes.
Still, even if you stick to any of the Story arcs inside the series, you should be fine.
The Reading Guide from LSpace.org is invaluable there, even though it is not completely up to date for the last couple of books.
I've attached it here to make it easier to see.
