How do you plan to get traffic to your website?
There are four primary methods:
Organic search - relying on Google, Bing, etc. users clicking on a link to your website. This is heavily influenced by SEO (search engine optimization) basically how well a page on your website ranks for a specific search term. 1st result gets most of the traffic, 2nd and 3rd result quite a bit and by the time you're on the second page maybe 1-2% of the traffic.
Referrals - links from other sites. This also helps with SEO.
Paid - Google adwords, Facebook ads, banner ads, etc.
Social Media - Similar to paid in that many social media platforms, i.e. Facebook, will limit how much your links are shared unless you pay extra to promote them.
Organic traffic is "free" but realistically you can have the best content in the world but if it's on a new site with no links from other websites and no traffic it will languish on the 4th page of Google and take months to climb up to the first page - if ever. If the first page results are all highly reputable sites you may never get there. Typically you need to plan on 6-12 months for a new site to start getting significant traffic even if you have great content from day one.
Paid traffic can obviously get expensive. "personal injury lawyer" or "best credit card" might cost $50-100 per click. On the other hand something extremely niche like "how to make trees for model railroading" might cost $0.10 per click.
Google Adwords advertising revenue is not going to make that much. It has one of the lowest bars to entry and lowest payment rates. To make more from display advertising you need to use other ad networks like AdThrive and MediaVine. However, they require 50,000 and 100,000 monthly sessions, respectively, to qualify. One source I found shower their average payment rates to be about $15 and $20 per 1,000 sessions, respectively. So if you have a website with 100,000 sessions per month you could make $2,000 per month, or $24,000 per year. Nice, but not exactly quit your day job kind of money by itself.
As far as tools to estimate traffic there are some free tools but most of the good ones cost money. If you have Google adwords account you can get some idea of traffic volume for a specific search term - say "inflatable kayaks". If that search term on Google gets 10,000 searches per month and you are creating a website focused on inflatable kayaks then projecting you will get all 10,000 of those searches is unrealistic. Maybe you can get 5-10% at first and eventually as much as 40-50%. But there's a lot of factors that go into that and frankly my knowledge is not very deep on all of this.
