Blonde BACK to brown..

Hey everyone, so in November I made the dumb decision of dyeing my hair blonde (I loved it... at the time) I realized a few days ago how much it damaged my hair and instead of keeping up with the blonde, I want to go back to brown, but not the EXACT same shade I was before.. I think I’d look better with some warmer undertones (my hair is naturally ashy brown). Any advice on how to get my hair healthy again after I go back to brown?.. I plan on not dyeing my hair again (MAYBE just some partial highlights later on)