Insecticidal soap works well, but make sure you wipe the soapy residue off after some time. I have burnt my plants before leaving some brands on. Ladybugs work well for aphids too, you can get them at grow shops or garden centers. If it's ants that are farming the aphids for food (you will know cause you will see tons of them) then you gotta deal with the ants first. Neem oil is probably the safest and best way to deal with them, but for some reason I can almost never find it for sale in my area.