I actually meant to read Discworld books at one point many years ago, but was always overwhelmed at the size of the universe.

Just pick one (preferably a one-off or one at the start of a series, thought at most you'll miss some character background and lore if you pick one in the middle) that looks good to you and start reading, they're all good.

The very first ones are a bit different than the rest, especially the first two (more genre parody than Discworld proper) as he was still finding his footing, but they're still good.

Guards! Guards!, Small Gods, Wyrd Sisters (technically Equal Rites is the first Witches book, but it's still a transitional one), Pyramids, Mort, or Sorcery (still a transitional one, but quite a good one) are good starting points.

Or if you want something with less books just pick up the Bromeliad, aka The Nome Trilogy; just three books, and a whole different setting, but also a classic. Not exactly the same style as the Discworld books, but they'll give you an idea of how you like his writing (probably more than the first two Discworld books, really).