Depends on the plant what kind of cutting you need, and until you know that,you can't do any cuttings - some need semi ripe, some softwood, some hardwood.

You don't say from what plant and it does make a difference.

In the absence of other info I'd pull off a few shortish (3 - 4 inch) side shoots, strip off the leaves from the bottom half of each shoot and stick them down the side of a pot of moistish compost with a plastic bag over the top, secured with an elastic band. Blow the bag up so it doesn't touch the remaining leaves and put the pot on a northfacing windowsill, so it gets light but not sun.

Hope for the best.