Everyday, i do natural bancklinks to my sites about 10 links per day or less if i am too lazy or don't have enought time.
I think if your backlinks are natural, created manually, not with bots or others cheats, Google won't ban you.
A 'natural' backlink is one that was created by someone not connected to your site ie/ not for SEO purposes. For instance if you made a really good post about something, and people linked to that post on your site to share the information, those would be natural backlinks.