Start with one page: the day in order
A handbook fails when the sitter has to hunt. Open with a single page that runs the whole day in time order — first check, feeds, turnout, egg collection, midday water check, evening feeds, lock-up — with the approximate times you normally do each job. A sitter who follows that page alone will keep every animal fed, watered and shut in safely. Everything after page one is detail they can look up when a question arises, which is a completely different job from guessing.
A section per animal or group
Write each section around what the sitter physically does. Feed amounts belong in the measures used on your place — this scoop filled level, half that bucket — not in weights the sitter cannot reproduce without scales. Name where each feed lives and which bin is which, because look-alike bins are a real farm hazard. Note the hierarchy honestly: which horse must be fed first or separately, which goats bully, which hen is broody and pecks. Cover water points, shelter use in bad weather, gates that must stay shut and gates that stay open, and each animal's normal so the sitter can spot abnormal — the mare who always finishes first, the sheep who always lags.
The emergency page goes near the front
Emergencies are when handbooks earn their keep, so put the page early and make it blunt: your phone number, your vet's number including out-of-hours arrangements, a neighbour who can come quickly, and where the animal first-aid kit, spare halters, torches and the fuse box live. Write short instructions for the three likeliest crises on a small place — an animal out on the lane, an animal found down or injured, and water or power failure — including the words 'call me at any hour' if that is what you mean. Also note what the sitter is authorised to do: call the vet at their own judgement, move animals between fields, buy feed if a bin runs low.
Leave the place ready to match the book
A handbook describing tidy labelled bins fails if the bins are neither. Before you leave, label feed bins and scoops, stock enough feed, hay and bedding for the whole trip plus a margin, park equipment where the book says it is, and walk the sitter round with the handbook in hand, watching them do one full round of jobs. That rehearsal catches the ambiguities no proofread finds — the gate that needs a lift, the tap that turns backwards, the pony who only looks fierce.
The version that travels with the sitter
Paper stays in the kitchen; sitters work in fields. KinsLe's Care Pass gives your farm sitter temporary, clear access to each animal's routine and key details on their phone while you are away, so the answer to 'how much does the grey mare get?' is in their pocket at the feed shed, not back at the house.