There are a few Ways you can go about it. Usually, most go from Book 1, which means The Eight Doctors. With the EDAs there are a lot more arc heavy from what I know, so reading it out of order can be tricky at times. Still there are some Standalone Books. I do recommend reading those two Posts here:
I think they are pretty good guides
Personally I think a book like The Crooked World is one I highly recommend, very Standalone and such a lovely Read really!!
I am sure you are probably aware but keep in mind that the EDAs are very different in terms of what they were able to get away with than like the Revived Doctor Books! Just something to keep in mind, I suppose!
Tricky Thing really, they can be very difficult to get physical copies. But then again it depends on the Book really. Stuff like Alien Bodies will cost you a lot, even in poor condition. I do say you will probably be able to find some on Amazon or eBay for a good Price or good Condition, but usually expect at least 10–15 Bucks for each, which is a bit expensive for books this old. Really if you are a Fan of getting a physical Copy it’s worth to give it a shoot, I mean it worked for me, got myself at least 20 EDAs for a good acceptable price. Although maybe wait before you buy more, read at least a couple and see if you like them!
Either way, hope you enjoy your Journey with them, still working my way through them and it’s a blast!