Question about backlinks for EMD niche blog

Hi guys. First post here, I hope you can help. I run a couple of small niche sites that rank well (1st page for main terms), but I'm not too clear on how to create backlinks myself. I used a service for a while but I'm sure I can do it manually too.

Is it a matter of commenting on blogs? A lot I see are NOFOLLOW, doesn't that discount them?

Any advice or tips on how to create backlinks Whitehat style would be great. Thanks in advance.