The guinea pig is a very endearing but also very fragile animal. If you choose to have one as a pet, you must be very gentle with them and avoid all stressful situations. However, they are rather easy to take good care of when you know what to do.
Like any living being the guinea pig needs to drink. To keep it fresh and clean, change their water every day. Note that their diet already contains enough water (there is plenty of water in vegetables), so do not be surprised if they don't not drink much. Precisely, vegetables are very good for their health, and they should ideally eat 100g per day. The guinea pig may be wary and refuse to eat vegetables if they are not used to them, but you must insist on offering them a little bit every day until they accept, increasing amounts gradually so as not to rush them.
Here are the fruits and vegetables that guinea pigs can eat without problems (cut and without seeds):
Tomato, celery, eggplant, cucumber, fennel, pepper, broccoli, iceberg lettuce, lamb's lettuce, arugula, turnips, radishes, zucchini, endive, strawberry, raspberry, apricot, pineapple, tangerine, quince, kiwi.
The guinea pig also needs to have hay to allow them to use their teeth. They will also need vitamin C in liquid form (ask your vet) every day in addition to their meal, as it is essential for the body. Seeds / pellets are to be avoided if your guinea pig does not spend much time outside every day.
Guinea pigs wash themselves everyday. Washing them is useless, unless they are really dirty. In this case, run a little warm water in a sink and gently wet their body but not their head and ears. Dry well with a towel if possible but never with a hair dryer as this is too stressful for them. Their claws must also be maintained. You can cut yourself if you know how (attention not to cut the pink part of the claw) or you can ask your vet to show you how. Feel free to brush your pet on a regular basis with a small comb if they have long hair.
Tip: Do not forget to clean their cage every week!