Should I rank categories/tags/searches?

Hi there. I am currently working on a new website. I was out from this busbusin and I am a little bit worried about a thing because i see many changes since I've been out from online.

Should i try to rank product itself, categories, tags, or searches, or blog content?

Talking about a WordPress eCommerce.

Also should I try to build back links for which of them?

What one did you recommend?

Many thanks and i hope I don't ask to deeply stupid questions .

:)