Vellum provides a wonderful journaling option, as it allows for perfect tracing. Simply lay the sheet of vellum over the alphabet you want and trace with a pen. You can print out computer journaling onto a piece of scratch paper, then trace.
Because vellum isn't as porous as regular paper, the ink often sits on top. I've had the most success with Zig Writers, Sakura pens, Zebra's Jimnie Gel Rollerball and Pentel Gel Rollers. Do your journaling, then let the piece dry for a few minutes before working with it.
While I can't speak for all brands of vellum, I can tell you that Paper Pizazz® vellum is safe to run through a computer printer. One caution is that it takes a bit longer for the ink to dry, as vellum isn't porous like other paper. Be careful when handling the vellum once it's printed. I usually leave it to dry for a couple of minutes. Fellow designer Arlene Peterson gave me these tips: