According to the French agro-expert Hervé Covès, the key to aphid control is to make sure you have aphids all season, especially early in the season! The reason plants like elderberry and nasturtium, which tend to have loads of aphids without being bothered by them is NOT that they "trap" aphids - the bugs on them are different types of aphid - but it feeds aphid predators.
Tiny flowers and umbellifers are especially useful to hoverflies and the tiny parasitic wasps.
He also points out that spraying the plant with a weak honey solution causes it to think it is attacked by aphids and thicken it's cell walls. However, this does come at a cost to the plant (but is better than being weakened by aphids).
Interestingly, he has observed that the presence of aphids without gap until the autumn has led to aphid predators eating the asian fruit fly drosophila suzukii, which is a recent arrival in Europe with a big impact on cherry, grape, and soft fruit.
Therefore my goal is to make sure I have tiny flowers for tiny insects, and to make sure there are always aphids somewhere in the vicinity.