Vitamins should be a part of your diet to ensure proper strength and nutrition is maintained. To aid in flushing your system, a hot drink about 15 mintues prior will help. It goes without saying that an enema should be done before engaging in activity to rid the system of any remaining residue in your intestines. Allow about two hours between your final enema and the beginning of play. If the hair around your butt is long, you may want to shave it as it may otherwises get pulled when a hand is inserted.
Many bottoms perfer a sling when available.
Another position condusive to fisting activity are doggie style, belly down and butt up. This position also provides the least bending of the rectum and often permits easier depth. This is usually a slow process. Start your entry with the fingers straight and the thumb tucked under. The fingers may slowly wiggle to aid in entry, gently massaging the sides of the anus.