Try analyzing your competitors backlinks, you should be able to start figuring out what theyre doing.
The fact is there is no step by step guide to SEO that is always going to work, there are some that will work for a while and then start to drop.
If you do some research you will find sites with terrible on site seo ranking for no.1, you will see sites with horribly spammy backlinks ranking as no.1.
Create quality content and then promote it through social media. The more traffic you can drive to your site yourself, the more google will think your important.
And as for forums, they may be no-follow but if you provide helpfull posts to your community, you may well find people from that forum visit your site to see if you have any other usefull posts.
Sent from my GT-N7100 using Tapatalk 2