Keyword selection is fundamental to success when it comes to executing a paid search or PPC campaign. It is also integral to a website natural or organic ranking on the search engines. But keywords are not just about SEO
Use keyword planner tool to choose good keywords.
I will suggest you for long tail keywords. It will help to rank your primary keywords and drive good traffic to your website.
First of all do competitor analysis and then pick the keywords in which they are ranking and in which they are running ads, after that you can use google keyword planner for this to get the best result and keywords.
For SEO keywords, you will have to finalize the theme of your website and then analyze your competitors website and then choose your keywords by using Google Keyword Planner tool
To choose SEO Keywords its depend on your topic because there are so many sites but the content is different that's why it's fully dependent on your topic.
Google keyword planner tool,wordstream are the tools used to choose keywords. Keywords are the primary part of the website for generating traffic into website.
Google keyword planner is best tool but you can also check your competitors keywords within there source code . Also when you search keywords on google it show suggestions at bottom.