What is better?

I have my main website that is in NO way SE optimised. I am targeting two particular key words (2 words + 3 words).

Would it be a good idea to create a niche websites to target these keywords, then link my mainsite on these niches sites.

OR

Advertise Only my website even if it is not SE Optimised. (I cant optimise it)

Whats better?

How can you not optimise your website? dont know how? have limited access or?

Depending on how you are going to target these keywords then especially is its new / unestablished with backlinks / pr, & your going to mass build links then I would have some type of barrier between your link building & main site.

Lol you're talking about keyword rich niche websites or advertising when you don't have your main site SEO'ed. How do you understand niche websites or advertising campaigns built around an unoptimized site to be successfull when you can't optimize a site? The basics of SEO is not really that hard.

Actually, on my main website 95% of my pages can only be seen if you are logged. I have only a few pages that you can acces when you arent logged.

It's why I am saying that it would be hard to advertise my website and get a good PR.

Of course, these pages are SEO'ed but there is only a few infos, and more images than everything else. I really want to keep everything everything clear & simple.

It's why I thought about a niche site where I could display alot of interestings articles about my keywords. I just dont want to have all these articles on my main website. They wont just fit there.