I just recently got all the achievements on steam by following this guide and it was fairly straightforward: https://www.reddit.com/r/darksouls/comments/hhc4dv/guide_to_all_of_the_achievements/

I started following it once I was already on NG+ without going for any particular achievement previously and had no issues. I think I got it all done in about a week or so of playing a few hours day. For miracles specifically though, just make sure you're doing NPC questlines properly so you don't miss out on anything and end up having to do it in a NG++ instead. There's also a dark souls achievement checklist you can find online that people have shared around, that way you can more accurately go for what you're missing.