Guinea pigs very quickly get used to a routine of feeding, cleaning and human interaction. They will soon be greeting you with welcoming squeaks when they hear you open the door or rustle the food and hay bags.
Human contact
As part of the GP care routine, you should check on them at least twice a day, morning and evening. Guinea pigs love human company, though, so the more time you can spend with them, the happier they'll be.
Feeding
Guinea pigs love their food, and eating takes up much of their day. It's at feeding time that you'll be rewarded with the loudest and happiest squeaks of all! Give them a bowl of dry mix in the morning, along with some chopped fresh food. If outdoors in their Eglu or other run they will be able to graze on the grass, and in the evening you can refresh their hay supply for overnight.

This brown Coronet Guinea Pig is ready to be looked after!
Fresh water
The guinea pigs' water bottle should be refilled daily, and needs to be available at all times. If the weather is cold, be aware that the water will freeze. You'll need to thaw and refill the bottle more frequently.
Clean the enclosure
Housekeeping and cleanliness is very important. Guinea pigs' bedding should be changed regularly. Guinea pigs can't be trained to use a litter tray, and although they may favor certain areas of their enclosure, they will go to the bathroom anywhere they like. The Eglu comes into its own here, being quick and easy to clean.
Lee, 26 September 2017
I take and put clean shavings in my piggies cage. I put clean shavings in the litter pan. Then I put it in the corner and sprinkle some of the soiled shavings over the clean in the potty box. They will use the litter pan more than the all over the cage. I have done this with several Guinea Pigs.