Typically, I'll just make sure that the content is informative and then look for sites that should link to that keyword and submit it.
so if the site is about widgets and the inner page is about red widgets, I would submit to both sites on the color red and also sites on widgets, just be sure to submit the inner pages URL and try to make sure that there are other useful pages linked under it with at least one of them linking to a high value site so the spider does not get stuck (the last part is just a theory of mine but after testing a working one).
Inner linking has really helped our SEO, I have almost every target word for all of our clients.
You should try for web directories submission for backlinks to your site's inner pages.
Article submission, blog commenting, forum posting can help you also if you are not able to do then you should hire any professional service provider because hardly up to $200 to $300 you can do all the process like directory submission, article submission, forum posting etc.