Hi. I've just had my hair highlighted ash blonde to blend in with a few grey hairs coming through. In between highlights use a purple or blue toned hair shampoo that will keep your highlights from turning yellow. If you try and lighten just the roots your hair will only go down a couple of shades producing a brassy colour. You could always try putting in a few of your own highlights at the roots. You can buy kits that you don't need to use a Cap for, just comb in the highlights where you need them.