up for this, none legitimate blog will hurt your serps. Also, make sure that your content is sharable and scannable.Tip #1 - make sure it's a real blog. There are real blogs then there are faux blogs set up for all sorts of reasons (but mostly for the purpose of selling links)
Only get links on the real ones
First thing you need to check is its relevance. Pick niche relevant guest blogs to get maximum benefits.
Also you need to check how real is the blog you're outreaching.. Make sure it has clean backlink profile and allows only niche relevant backlinks.