As title mentioned, I want to rank keywords for webpages and categories on my blog, should I build backlinks for all pages or only homepage?
Please share your advice.
The best advise I can give you is to learn link structure or on-page link building and that should help you answer that question.
You can link to inner pages and still pass that link juice to the homepage and link to the homepage while passing the link juice to inner pages depending on your website structure and navigation. So basically, with a good site structure you wouldn't ask that question. Simply do some research on how to structure your website for good seo.
Try to build backlinks for all the internal pages, instead of the home page. Because having specific pages for targeting specific keywords will help to obtain keyword rankings even faster. Also, it will definitely help you to avoid unnecessary Google penalties.
Lets turn the tables for a moment and think about this logically...
Lets say you come across an amazing informative article and you want to mention it on your blog... Are you going to provide the home page URL or the exact URL to the article? In a similar way lets say you come across an amazing product or service and you want to recommend it on your blog... This time round which URL will you provide - to the home page or to a blog article??
In addition do you think that your home page should rank for all of your keywords? How many times have you landed on a webpage which wasn't the home page... Way more than you realize ;-)
In simple terms its about matching your keywords to the most relevant content/page... In otherwords its the best page on your website which should appear in search engines for a given query... Get that wrong and your backlinking profile will for sure not look natural and easy to spot algorithmically....
You should build backlinks for all pages because you are ranking for more keywords and more pages, not only homepage.
Each keyword should be focused on a page or a category, my team is applying this way and getting more good results when all our keywords increased and more keywords listed in top search engines.