The thing I discovered while falling down this particular rabbit hole is that 'Alice in Wonderland' isn't a series per se. Lewis Carroll published two books: 'Alice's Adventures in Wonderland' first, and then its sort-of sequel, 'Through the Looking-Glass, and What Alice Found There'. That's the strict publication order. Some editions, especially older ones, will bind them together as one volume.
Honestly, the Looking-Glass feels like a companion piece more than a direct continuation. The tone's a bit more melancholy, the logic puzzles are even weirder, and it ends on a note that's stuck with me ever since I was a kid—that whole 'life, what is it but a dream?' line. I'd suggest reading Wonderland first simply because it introduces the core nonsense. After Wonderland's chaotic tea party and trial, Looking-Glass's structured chessboard game lands differently.
There's also a ton of spin-offs and retellings, but for the original texts by Carroll, it's just those two. Don't overcomplicate it; start at the beginning and see where you end up.