H1 tag is pretty important for SEO purposes. Think of it as a first child of a family and he/she will represent the whole family or content. H1 tag should consist of your main keyword or phrases. It helps Google to understand what really is your content about. To learn more about H1 tag you should read this article.
H1 to H2 heading tags are very important for an article, Heading tags it should be used with the keyword, description or tags. It helps Google to understand what about the content what user want. that's the way Google understand user problem.
Each page needs to have only one H1 tag. If you are using WordPress then by default the title of a page is wrapped into H1 tags.You can either choose to have the same <title> and <h1> tag or provide an alternative title for the heading.
As far as the other headings are concerned (h2, h3), the things you need to have in mind are the following:
*Avoid using a single word for a heading but make your headings interesting and useful for users that like to skim read an article.
*Use headings hierarchically i.e. the first heading tag is the <h1> and then the <h2> and then <h3>, <h4> etc.
* The subheadings are a great place to use related keywords in your content.
An H1 and H2 tag are very important for every web document to structure the content as the heading acts as an information guide for the search engine bots. It should include competitive keywords. Also, it can be placed anywhere so long as it is unique, using only one per page and holding 70 characters tag length.
H1 is highly important that H2. Well both tags can boost SEO.You Should insert major keyword in H1 heading tag. Secondary keyword should use in H2 heading tag. Also consider words length for headlines that works rightly for SEO.