Any notepad/book will do (old bank transaction slips, receipts, pieces of a paper bag), but using one's left hand while writing a language that reads left to right requires a pen whose ink dries on contact as quickly as possible. Pilot's V5 Series has been my favorite for almost 10 years now. :)

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)