Just practice. Dry fire practice as well.
I switched for the same reason. My right eye still thinks it's dominant but its vision isn't even close. I now shoot better from the left and instinctively shoulder on the left. That took a while.
Archery was more difficult but not as bad as I thought it would be. I'm probably five years into it and I doubt I'll ever be as good left handed as I was right handed but I'm decent.
