You should concentrate on your content. This is the method recommended by Google and any other thing might get you a penalty if you don`t know what you are doing. You should avoid at all costs blog commenting and forum commenting if you don`t want to have problems in the future (if some "guru" recommends this practice, just turn around and walk away, they don`t have a single clue about SEO). If you don`t want to listen to me, just find someone with a PBN and buy some backlinks from them. But first, you need to document yourself about the risks of this method.
Instead of putting energy on backlinks, put it on contents, instead of spending money on backlinks which is very unsafe, hire freelancers and spend it for high quality content, remember that Google search results ranking algorithm may change at any time, the ones who follow some spammy link building methods always get problems after every update of Google algorithm, better concentrate on content, Facebook ads, and promoting your websites on social networks by building real communities and followers.
You have a better chance at getting duplicate content indexed compared to relying on a link builder that is unknown, and get you penalized in the future....
Find Quality backlinks is always a tough job for Linkbuilders but the simple way to find quality backlinks is to track back your competitors by any backlink checker tool and follow the footprints.
Danasurvey is correct! All links must be relevant. For example if you put a "dofollow" comment in someone else's blog about horses and link to your page about airplanes, you will likely get penalized because there's no relevance
First of all, there is no such thing as a "dofollow" link. There are just normal links and links with the "nofollow" attribute. Secondly, you won`t get penalized if you link to your page about airplanes from a page about horses. You will receive traffic that is not targeted, that`s about it.
Maybe you can use keyword for your baclink and improve your traffic! Also, your web site must be trusting in Google!