Firstly, Treatment for aphids is similar to treating mites. Pinch or prune off heavily infested leaves or other plant parts. Look closely, as aphids will usually be found under the leaf or on the stems.
Do your best to stabilize your grows temperature to 20-25C (68-77F) and increase airflow.
Lay or hang sticky traps (yellow or blue)
Before using any harsh chemicals, try a homemade 1:3 vinegar-water mixture and either spray or wipe your plants. A similar spray can be made with dish soap instead.
Applying Diatomaceous Earth (DE) is another organic option. Powdery rock sharp enough to kill small pests. Use a brush to brush the DE over the stems and the leaves. You can even just sprinkle some right onto the big leaves. Even apply some over the top of the soil if necessary.
Predators like Green Lacewings, Orius Inisidousis, and Ladybugs are great for controlling the population. For best results, make releases when pest levels are low to medium. Attacking them early in their life cycle will deliver the highest success. The predator bugs are harmless to your plant and are another organic way of pest control.
For outdoor growers, Bug Blaster to hose off plants and any bugs that are hiding in the foliage could work.
Chemical-based foliar sprays like Doktor Doom, Safers, Spinosad or Neem oil could also be used when other options are not working, and the problem needs to be resolved before it gets out of hand.
If aphids are a recurring problem for your grow, consider growing companion plants like Cilantro, marigolds, basil and peppermint.
A crucial point of prevention is never to bring outdoor plants inside. Even if you are cutting clones, you must be very careful and diligent in ensuring you aren't bringing anything in with it.