Now you understand types of content and you can start to look at content options and when you start a fresh website you would like to find the best content that you KNOW you can rank.
For me, this will always be informational content, the problem with a vast amount of buyer content is that it has money behind it so they will need more work to rank as they may need links to overcome competition and reach page one.
Informational content also can help pull in people who may be just before the purchase stage and the content you write and link to may be able to convert this traffic better than pointing them at a buyers keyword along with giving you more pageviews.
While this is a manual process it can yield very amazing benefits and an amazing amount of searches when you find a key phrase that users are searching for frequently on Google.
Google Auto Complete is the phrases and suggestions that Google will frequently give you when you type into the search engine search bar, they are phrases that are being typed enough to have Google key on them.
This method will take you some time and documentation with a spreadsheet like Excel or Google Sheets so that you can record the keyword phrase and the competition you see within the SERP, this will help you know the word total and what is expected in the SERP.
This method can help you when starting to find long tailed keywords that you can then investigate further and figure out whether they are good starter posts for your website or whether they should be saved for later.
This can involve tools like AnswerThePublic, AlsoAsked, and Google Trends. Each of these tools can help you take a seed keyword and expand on it to show you more longer tailed searches that are more targeted.
These tools can help you look and locate keywords while also providing additional details like how easy they may be for you to rank in the Search Engine. This comes at a cost though as these tools aren't cheap and I wouldn't suggest them for new niche site builders.
This includes tools like
SEMrush,
KWFinder, and ahrefs as big players in the space. I have used all three of these over time and currently only use SEMrush as I found it the most organized for myself, I have friends who swear by both other tools.