Gather up as many different inks, papers, nibs, and nib holders as you can. It might be a good idea to get several scribes together and experiment with each others' materials. Include such things as a variety of calligraphy inks, period inks, paints, felt tip calligraphy markers. Also get together as many types of paper as you can. Some examples are...watercolor papers (hot and cold press..various weights), vellum scraps, bristol board, printer paper, and handmade papers.
Ink up your pen and start writing anything. This excercise is to explore different materials, so the quality of the calligraphy is unimportant. Try the ink on every type of paper. Clean your nib and try the other inks, one at a time, on each of the papers.
This will give you an idea of how important ink and paper selection is. You will see the difference between good ink on vellum and markers on cheap paper.
Borrow books from libraries, friends and other scribes. Whenever scribes gather, ask them to bring along one or two books to share. Look at as many actual pieces as you can. this will help develop the way you look at a Medieval piece. To the modern eye, Medieval pieces may appear unbalanced. To the trained eye, modern attempts at a Medieval piece look strange.
Use the best materials you can afford. In general you are paying for quality. Quality often translates to, easy to work with, convenient, and a long life to the finished piece.
Use a cake decorating tip cleaning brush or an old soft bristled toothbrush to clean your nibs after each use. Many inks are corrosive.
Always use distilled water to clean brushes.Tap water contains chemicals, one of which is usually chlorine (as in bleach). The water will carry the chemicals into your paints. Eventually, the colors will be affected.
Use a thin, hard lead to draw on your paper or vellum. A .03 HB mechanical pencil is great. It will give you just the faintest line and too much pressure will break the lead before it can leave an impression in the paper.
Never try to erase a paint or ink mistake immediately after you make it. To avoid spreading the offensive pigment, make sure it is completely dry (as in overnight) before you attempt a repair.
Use a soft, white eraser. The pink rubber erasers contain dyes and chemicals which will affect your paper or ink over time, but may not be immediately apparent. White pen erasers are too abrasive, and will pull up paper fibers as well as pencil marks.
You can erase ink and paint off of paper. If it is not a major mistake, try an eraser. I was ecstatic when I found that light smudges can be erased. If it is a serious mistake, patiently and carefully scrape the ink off of the paper with a sharp edge (razor blade, craft knife, etc.). Erase in a circular motion to pull up any loose paper fibers. After making sure there are no more specks of ink or eraser crumbs, deeply exhale onto the roughed up area and burnish (rub smooth). If you don't own a burnisher, any clean, smooth piece of glass will do. Once in an emergency, I used the bottom edge of a drinking glass.
Breathing on the paper imparts a little moisture to the paper.The moisture from your breath and the heat created by burnishing restores a smooth finish to the paper. You can then write or paint over it if needed.
Make up some "throwaway" portfolios out of cardboard to give to people to carry scrolls home in. Label them all with "Please return to the nearest scribe for recycling". You don't have much invested in them if they disappear into the great beyond, but it may get a piece somone has spent a lot of time on, safely home from an event.