I deal with small business owners on a daily basis. Their knowledge of SEO varies greatly as does their competition in the SERPS. I will tell you that it is tough to give complete answers without first knowing how competitive your niche is.

Advice:

If those 50 domains are to be of any use, you will need to promote each of them first. Setting up a site without any promotion just to link to your main site is a losing strategy and one that will leave you pulling your hair out.

It will not be helpful unless those sites are individually promoted first. That can be a monumental task, depending on many variables.

My deduction, without the minutia... It sounds like a better investment of your time may be to promote your main website first through other relevant media.

All of this depends on many factors. Would be glad to help you sort it all out on a call.

The problem with Odesk and Fiverr is that all of those freelancers offer you "mechanical" solutions which in essence translate either to number of link builds or content written in any of your blogs or websites. The trouble here is that Google is getting smarter and no longer falls for an extra number of links or just more written content (remember the last penguin update on Oct 19, it penalizes "thin" content websites).

What you need is a strategy and that strategy can only be conceived by knowing the following:

1. What keywords or terms are you trying to rank for.
2. Is there really a significant volume of searches being produced for the terms you want to rank
2. How well is your competition ranking for

The end result could be a combination of several efforts, a little bit more content on your website or probably placing or creating your content on other sites such as Youtube, Amazon, or other networks (That is actually what I did with my own site and was able to piggyback Youtube until we reached 1M uniques/month on our own site).

So here is what I do, research what keywords you want to rank for (volume of search and what other terms are people searching for. Market samurai is a great tool http://www.marketsamurai.com/c/hernan and actually just by watching their tutorials you will learn the intricacies of SEO. With this tool analyze your competition and watch what type of content they have and where they have it. You could easily conclude where the big opportunities are, maybe its on Youtube or listing your store on Amazon. The level of difficulty can be assesed in colors as seen on this demo:

http://www.noblesamurai.com/share/seo-competition/aizoaq7zjaos88008cww#historical

I would focus on your main site for right now. Make sure all of your citations(NAP - Name, address and phone number) are correct and if you don't have any add them! (Yelp, etc).

Use Google My Business, this will help get your business set up on Google (Not the serps, but Google Plus, etc)

I would start putting out quality content related to your niche and start reaching out to bloggers in your niche with blogs that have high domain and page authority.

I'm guessing the other domains you have probably don't have any domain or page authority, so I don't see those backlinks helping you at all.

Word of advice. You may find gold on those sites, but you're more likely to hurt your site when Google throws another update out and you find they used some black hat methods!

I own a small local business (brick and mortar) and have firsthand experience trying to "crack the code" of online marketing and specifically with increasing Search Engine Rankings.

After having enlisted the services of several experts and completing hundreds of hours of hands-on experience implementing and tracking several different strategies I discovered what works (at least for my business).

For details let's set up a call... In the meantime here are some tips you may find helpful:

1. Use a Multi-Faceted Strategy

Lots of "experts" on SEO are really experts in one very specific area of SEO - like building citations or backlinks etc. But any real expert in SEO will tell you that (1) it requires several core pieces to be optimized (that's what I meant by "multi-faceted") and (2) it is not a "quick fix".

2. When Using Fiverr gigs (or similar) Make Sure You Have Laser Focus

Remember that you are hiring a specialist to perform a very specific small scope project. It's just checking off one tick box in the list of all of the components of your plan.

Also - be reasonable about your expectations. After all - you don't really expect an investment of $5.00 to translate into the thing responsible for generating $100,000 in revenue... Do you?

3. User Experience Matters

Remember to include things that improve the User Experience in your plan. Things like how quickly your page loads and website layout matter.

Best of luck!

We would probably need more information to really answer this fully however in general I would say to make sure that all 50 citation page entries are entered exactly the same and complete. If you don't know where to find those drop me a note and I will share the information.