Guinea pigs are not starter pets, but require time and effort. If you are willing to give your guinea pig a good home with proper food, attention, living space, and vet care, you will be well rewarded with a happy, healthy, long-lived pet.

[edit] Steps

Get large enough cages. You should allow 7.5 square feet of cage space as a minimum for one guinea pig, or 10.5 for two. However, the bigger the cage the better. If cages are the minimum size, they should have some floor time each day — let them loose in an enclosed space. A bathroom is fine, but line the floor with rugs or towels so that they have traction. A hutch is fine in summer, but don't leave them out overnight if it gets down below about 5° C, as they may die of cold.
Adopt two or more guinea pigs so they are not lonely. Guinea pigs need company because they are herd animals. If you just have one pet he/she constantly and learn to mimic their sounds so he/she doesn't feel too lonely.
Spot clean their cage at least once every two days, removing droppings, and food from the day before, cleaning the water and replacing hay if it has run out.
Clean the cage thoroughly at least once a week.
- Use a vinegar and water 50/50 mix to spray and wipe the cage occasionally to remove urine scale from the cage bottom. No harsh chemical cleaners are needed.
- Use CareFresh, fleece, towels, aspen shavings, or newspaper for bedding. You can also use shredded paper on top of the newspaper. Do not use wood chips for bedding.
Guinea pigs can get mites. Excessive scratching is a sign that a guinea pig has mites. Take your guinea pigs to the vet for proper treatment. Make sure all guinea pigs are treated at the same time as mites will spread from one guinea pig to its cagemates.
Trim toenails every month. If they have dark toenails, shine a flashlight behind the nail so you can see where the blood vessel ends: if you clip too close to the vessel the toe nail may start to bleed.
Feed good quality foods and hays. A good feed company is Oxbow. Avoid pellets made by Hartz or Kaytee as they contain corn meal, which can harm a guinea pig's digestive tract.
Unless you are breeding guinea pigs, don't keep guinea pigs of different genders together. You can keep them together if one or both has been spayed or neutered.
Let them play out in the garden - if you have grass they will happily eat it, so get an outdoor cage or run for them, with at least one hiding hole for them to get out of the sun, or if they get scared.
Check male guinea pigs every so often around their genitals, as they can get impacted. You can simply massage the area a little and if soft poop-like stuff is present, gently clean out the pocket with a cotton swab.
Keep their water clean and full - get one of those bottles with the little ball in the spout and keep it full. Be sure to clean the nozzle frequently to keep it free of hay and pellet gunk which can breed harmful bacteria and clog the water flow.
Make sure the guinea pigs get Vitamin C daily. Fruits and veggies like oranges are high in Vitamin C and good food for your guinea pigs. Give a variety of fruits and veggies. Each guinea pig will require 1 cup daily. Avoid iceberg lettuce as it contains too many nitrates that could seriously harm your pet. Too much veggies and fruits can result in diarrhea.
NEVER, EVER, feed your guinea pig celery. They can choke on the strings, which can be fatal.
Make hay available to your pigs 24/7. Guinea pigs are grazing animals so they need something to graze on.
- Alfalfa hay should be fed to babies 6 months old and younger.
- Timothy or bluegrass hay should be fed for guinea pigs older than 6 months. It should be fed 'free choice', which means they have some in the cage all the time.
Feed alfalfa pellets daily to guinea pigs under 6 months of age. After that, feed timothy or bluegrass hays. Do not feed rabbit or other small animal pellets - the vitamin content is not the same, and can be harmful to your guinea pig! Feed a plain pellet, as pellets with seeds in them could cause choking. Pellets, hay, and fresh veggies/fruits are all the food guinea pigs need.
Do not house your guinea pigs with rabbits or allow the two species to play together. Rabbits naturally carry a bacteria that can make guinea pigs very ill, and rabbits are bigger, stronger animals. Even a playful kick from a rabbit could kill a guinea pig.

[edit] Tips

Some Guinea Pigs may give you an exploratory nibble, don't worry. Once they find out you're not made of food they'll stop.
Towels or fleece can also be used as cage liners - just dump the bedding, wash and reuse.
For daily exercise, put them on the floor with a safe surround. Guinea pigs love to run. Be mindful that they might nibble electric cords and don't forget to closely supervise them whenever they are outside their cage.
NEVER use exercise balls or wheels. Even though they are marketed towards guinea pigs, they are not safe and can cause foot, toe and spinal damage.
Guinea pigs will eat their own poop; this is called coprophagy and it is quite normal. You may often notice them reach over their backside, but don't be alarmed. When they ingest their poop they get important nutrients from the bacteria in their gut.
If your pig suddenly leaps into the air or rapidly twists its neck with a little hop, it is not having a seizure. 'Popcorning' may either indicate happiness or an attempt to release excess energy, similar to a cat suddenly getting the urge to race through the house.
Guinea pigs also enjoy toys, which can be purchased or made depending on your budget. The less complicated the better. Empty cylinders and paper bags make perfect toys and are always welcome.
Get a heavy bowl for your guinea pig's food. They can chew a plastic one to bits, or knock a light one over. Of course, more entrepreneurial guinea pigs may knock it over anyway in order to get to all of their food.

[edit] Warnings

Never use sawdust, or corn cob bedding. NEVER use plastic litter or most anything else in the cage, as guinea pigs will chew it and can suffocate on the chewed pieces.
If a guinea pig gets sick, it can become worse or even die very quickly. If you notice that your guinea pig has crusty eyes or nose, this may mean it has an Upper Respiratory Infection and you should bring it to a reliable vet very quickly.
Don't be frustrated if they dive under cover whenever you approach. Guinea pigs need some time to warm up to you. It is also a matter of instinct and personality. Being prey animals, guinea pigs see looming shadows as a threat first and a friend later. Some will always resist being picked up, while others will approach given time to learn (especially if they figure out you're the food source).
Do not feed guinea pigs potatoes, onions, leeks, tomato plant leaves, chocolate, corn, wheat, dairy products, meat, mushrooms or iceberg lettuce.
Guinea pigs are fast runners, and they can outsmart you once you let them out of their cage, so be EXTREMELY careful!
Put down a towel when holding them so you don't have to go change if they pee or poop on you.
Never leave a guinea pig unattended on high places.
Please remember that there's an OVERPOPULATION of guinea pigs. Many are in rescues and shelters looking for a good home. Adopt your guinea pigs instead of buying them, and PLEASE DON'T ADD to the overpopulation by breeding.
Also be very careful if you must buy a pet store guinea pig that it does not have diseases. Check around the nose, the eyes, and the ears.
You can help save even more guinea pigs by looking around your local pet store. Be sure they all have food, water, and show no signs of sickness. If they do, alert the manager of the store immediately.
If you're giving them grass, make sure it does not have chemicals put in. The fresher the better, too!
Always clean out the cage every three days if you use straw bedding as it can have maggots in it.