In SEO, we optimize for 3 types of keywords:
With informational customers are just searching for information while in commercial customers are actually looking to solve a problem they have fixed a door in their house, in branded keywords customers are looking for a specific brand.
We want to:
1. Find keywords in one of first 3 categories.
2. Rule out keywords that we wouldn't have the budget to fight for.
Estimate what happens if you are number 1
Then, once you have found the relevant keywords you want to estimate what would happen if you are now number 1 on Google, how much money you would make for this we have tools that would assist us, one of these tools is named SEMRush.
To look for good keywords we can just brainstorm for keywords put yourself in the shoes of the customer and ask yourself what would you search for, don't try to be too clever, aim for regular customers with most traffic? For keyword suggestion and ideas, you can also use Uber suggest tool.
The next step after you have found candidate keywords is the bottom line, how much money would you make if you get to first position in google with these keywords, you want to first find keywords that would actually make you money and only then put months in optimizing them?
For that purpose, again we use SEMRush tool with this way you have a glance into the currently first position in google first ranked website, and then you can calculate how much money you would make if you get to this first position.