You can skip Touhou 1 (Highly Responsive to Prayers): If you can´t read japanese, you won´t be able to read the endings (also, it´s quite different from the rest of the series).
You *can* start to play at Touhou 2 (Story of Eastern Wonderland) if you have the pc98 emulator AND the english patch.
But yeah, it doesn´t hurt if you skip the pc98 part (Touhou 1-5) altogether and go straight for Touhou 6 (Embodiment of Scarlet Devil (The one where Remilia and Flandre appear first)) (You should get the
Retexture Patch 0.3 for that one). (Don´t skip from here one or you miss part of the story (at least that´s my opinion) (and you get used to the "improvements" of the later games, which makes the older ones harder))