There are a variety of ways to deal with aphids, from squashing them manually to any number of sprays but here is one very effective means of controlling aphids:
Ladybirds! Ladybirds love to eat aphids and they do a really great job of clearing them up. Don't be too concerned if you have a few aphids hanging around because if you always have a few (not enough to do much damage) there will always be a constant food source for your ladybirds and they'll hang around more permanently.
So if you have an aphid problem, regardless of what kind of aphids are attacking your plants, plant companions that will attract ladybirds. Coriander is a fantastic option. I like to have at least one ladybird attracting plant in each of my garden beds to ensure I don't get build ups of aphids.