If you are fortunate to have a team of helpers, then you will need to do some basic preparation for them in advance.

Numbering the graves

It is a good idea to number each grave with a plant marker before work starts. This includes the graves for which there are no stones. The small white plastic markers are ideal, and a number can be written on with a soft pencil. (Felt-tip pen washes off in rain, unless it is a special waterproof marker pen).  If the grass is long, then you may need to trim a small area with garden shears before "planting" the marker. Do not under any circumstances mark the stone itself.  Markers can be quickly and easily removed once the job has been done, with no evidence that they were ever there. It has been suggested to use strips of masking tape stuck to the stone, but I would disagree with the use of anything such as this.

Clearing the site of vegetation

It may be necessary, especially in the summer months, to clear some of the vegetation around the base of a stone so that the inscription can be read easily. There should be no problem in agreeing with the vicar or churchwarden that this can be done, and the best tool for the job is a pair of garden shears. Brambles are more difficult, but again there should be no problem in removing them with a pair of secateurs, although you should agree where the clippings are to be put, rather than just leaving them on the ground where they fall.

Some other types of vegetation do present a problem. In particular ivy, which may be clinging to the surface of a headstone. Pulling it away can sometimes also pull away the surface of the stone, together with its inscription. I have known a vicar of a church who wanted the ivy to remain on the headstones. There can, however, be little doubt that the "suckers" on the ivy cause more damage to the surface than natural weathering. The point here, is ask the vicar's opinion before you remove any ivy.

Lichen is a totally different matter. Our graveyards are often the only remaining habitats for lichens in the area. Some of them may be quite rare. If in doubt, never remove all of the lichen. I would tend to remove perhaps just enough to be able to view the inscription, but no more, and even then, it should be done very carefully with a small wooden stick. Lichen is protected by the Conservation of Wild Creatures and Plants Act 1975 (UK). A booklet is available from the British Lichen Society (bulletin 13, December 1973). The Society do respect that some lichen may have to be removed from a stone to record inscriptions, and they have no problem with this, but no chemical whatsoever should ever be used on a stone. The British Lichen Society would also like to be informed of any graveyards which are to be cleared for re-development.

Some stones in some graveyards are laid flat on the ground rather than standing upright. This can present a problem in that the surrounding grass will have crept over the stones in the course of time, often obscuring all but the central area of the stone. You will need to agree on a strategy with the vicar.  Are you to cut back the grass and its mass of roots to the edge of the stone, or are you to lift it temporarily and then return it in place after making your record. There can be little doubt that a stone covered with a root mass of grass will have its inscription in better condition than a bare one! Perhaps that answers the question.

Never use any chemical or rough abrasive on stones. Not ever. I have seen all sorts of things suggested, from shaving foam to detergents, rubbing the surface with grass or mud, chalk, charcoal, a scrubbing brush, and so on. Just don't do it!

Organising teams of people

If you have the luxury of several people to help you, then organise them into pairs. It can be more fun working in pairs, and two brains are better than one when it comes to deciphering the difficult inscriptions. The person who did the writing should always read the inscription back to the other person as a double check for accuracy, spelling difficult words and surnames. One of the team might also be usefully employed as a photographer. Checking is mandatory. Ideally it should be done by someone other than the person who recorded the inscription. Try to recruit as many people as is practical, but also be aware that local people might not like the idea of a crowd of people trampling around their graveyard. This can be a sensitive area.