I see two main approaches to consider:
1) is the Hubspot Product-Market and Model-Channel approach or Growth framework. It is good if you don't know your final product and you do marketing at the same time with development. Here is a big post.
2) Another approach is named as growthhacking or Bullseye framework. It is good for services which have already stable product. You think about channels, select best, test, and double / triple in case of success. You can google for more details. Do not find best link now.
Great content, also called ever green content is never obsolete. It can work for you for ever.
Creating authority and building your SEO takes time. I recommend you start ASAP.
I use ahrefs for connecting with influencers (search backlinks of your competitors), researching keywords and more. You can see some of the top ranking articles are a few years old.
Here is my research on marketing. You can find lots of great articles on growth hacking.
For networking work in shared space offices and lot of networking meetings.
Write How To blog posts. Curate and use your curated articles to build sky scraper type blogs. Here is our chrome extension called kurator.