To prepare for fisting, one should clip their nails as close as possible, keeping them trimmed with no sharp edges, since there are places in the vagina that do not have many nerve endings and might not be able to tell if scratching occurs. Make sure to use whichever hand is smaller.
It is important that the person receiving the fisting drink plenty of water and be ready for play.
Another important thing is to make sure to use plenty of lubrication. If not enough lube is used, the vagina could tear as the hand goes in. Another trick is to put lube in the palm of your hand so that it goes into the vagina when the hand changes over to the fist shape. This is important with fingering as well, which is how fisting should begin: slowly and carefully, building up to the next stage. Make sure that your partner is enjoying it, and do not try to force anything right away. If the other person is too nervous, go more slowly, or try other things they enjoy. Remember, the vagina is going to be stretched much farther than it is normally expected to be, so it will take time at each stage of penetration. If at any point, the vagina clenches tight and tries to push the hand away, slow down and do not try to push farther. Once the vagina has stretched to be able to handle four fingers, use more lubricant to cover the hand and up past the wrist. Then make a duck-bill shape with your fingers, and begin easing in with that shape, pausing when necessary to allow the vagina time to stretch, maybe even opening up the hand a little to stretch inside. The hardest part will be the knuckle on the thumb, and it may be easier to insert if at this time you turn the hand a quarter turn clockwise while gently pushing. Again it is important to go slowly. Once both parties are ready, have the fistee take a deep breath, and push while slowly allowing the hand to close into the shape of a fist. Do not clench the hand. For a moment it will feel as if the vagina is being spread farther than it can handle, and then once the hand is in it will take several moments for the person to calm down, and be able to relax and enjoy it. This is the part where both people can really stop and enjoy the action. Usually, not much movement will be able to be done, but some movement of the hand could be pleasurable, but be cautious as it could also be painful. When finished, the hand should be removed in much the same way as at was put in. Do not remove the hand while still in a fast shape, go back to the duck-bill shape as much as possible, and again go slowly. Some force may be required, and try to help the person be as comfortable as possible and take several deep breaths.
(Personally, once the hand is removed, I gush if fingered immediately after, but it will be pretty painful to be fingered at this point.)
Fisting is a very intense type of play, and both people will likely be in need of aftercare, a shower, and probably snuggles. It can make the recipient very tired and also very hungry.
People point to pregnancy often when speaking about fisting, but it is a very different case, as the female body has specific hormones released to help the body stretch during childbirth. Also, tearing is common during childbirth and should not occur at all during fisting if done correctly.
