i have a deep natural red colour, i try to keep my colour as natural as i can, i use herbal ACV rinses once a week. it seems to help my colour really shine!
i would say to use henna mum does that, she mixes the colours though always ends up having beautiful red high lights, (she does it to cover her gray, though the gray turns to red!
if you want to try somthing else, then maybe beetroot, carrot hair rinse. try adding hibiscus to it as well, do this twice a week if youve got the time. it might take awhile but you might have a bit of luck