As has been said, Upwork and Elance are very often a race to the bottom as far as rate is concerned. (BTW, Upwork owns Elance and is in the process of shutting it down so I would not focus on Elance at all.) I have used Elance to round out my portfolio, allowing me to take on projects in areas that I wanted to build experience. Thought the rates were lower, I have been compensated for essentially learning. I have also made a few contacts that have lead to better opportunities.

Three things I recommend:
(1) Use Upwork to build your portfolio while earning some income.
(2) Differentiate yourself as much as possible - I have gotten a more premium rate by demonstrating a better ability to deliver and higher quality. (Many people have had bad experiences with lower cost labor and are looking for a better option.)
(3) Take time to build relationships with customers. It will often lead to a greater opportunity.

I have participated in marketplaces that charge for access (subscription fee) and ones that do per transaction charges. I have found that I prefer the per transaction charges as I am essentially paying a commission for the lead / opportunity, which is much more palatable. I have worked with platforms that charge a fee for leads, which is more akin to a subscription fee. The problem is that you are asking providers to pay for the hope of making money where as on the per transaction you are asking providers to pay for actual revenue.

Elance and Upwork have a hybrid model that also seems to work well. You can bid on so many jobs for free and pay a percentage of revenue. They have higher levels where you buy more credits to bid. On Elance I started on the free level and had success so now I subscribe. This is an interesting form of the freemium model.

Hope this gives you some insight. Let me know if I can be of further help.

The better question may be why can't you find startup co-founders? I can see two main reasons why this might be the case. First, no one else sees the same opportunity. If this is the case, you may be on to unique value that no one understands, but that could also include the potential market. If no one else sees the same market opportunity you do in your startup, you will want to do more research to ensure you truly have a marketable idea.

The second reason is that you don't have a big enough network to find co-founders. This will also be a barrier to launching a startup. For a startup, the network of the founders is essential for both tapping into experience / skills the team does not have as well as for helping develop the market. If this is the case, building your network should come before building your startup.

I hope this gives you some useful things to consider. Let me know if I can be of further help.

You can use web sites such as Kickstarter to "pre-sell" memberships just like is done for other such products. For the "pre-sell", you may want to offer a special deal for being an early adopter.

There are also other sites, such as Fundable, that seek financing for the business.

Let me know if I can be of any further assistance.

Just to add to the great answers already provided, finding influencers (generally, bloggers) to review and recommend the app will go the furthest to gain momentum.

First, if your business plan depends on sales via your stockists, you want to make sure the methods you undertake do not undermine this revenue stream. Most merchants do not relish competing with their suppliers, though in this day and age is more expected. (When I was acting as a reseller, I started purchasing from Amazon.com because the pricing beat my wholesalers, who were also competing with me.) So, when determining your direct strategy, keep this in mind.

With this in mind, the next step is to build a direct sales strategy. This really only has two pieces. The first is determine how you want to differentiate yourself. Generally, when the wholesaler sells direct, the differentiator is price, i.e. "buying direct saves." Of course, you can differentiate on many fronts - customer service, speed, shipping costs, etc. (Just be sure that your pricing / terms don't alienate your stockists.)

The second piece is simply marketing the differentiation. For example, if the focus is on better prices, wholesalers will brand their stores as "Outlets", "Direct Centers", "Buy Direct", etc., which are associated with such savings. From there, it is a matter of creating and advertising mix that combines audience (keywords / demographics) with messages (ad copy / landing pages.)

Hope this gets you started. Let me know if I can be of any further assistance.

The first thing to determine is what is your motivation for starting a business. If you are wanting to create an entity that have value beyond your efforts (something that has stand-alone value that you could sell), the key focus is determining a need you can uniquely meet with a big enough marketplace to be financially worthwhile. You can self fund for a while but would need to be able to over operating costs, including your own compensation needs, before your own funds run out. Or, you would need to able to attract investors to do the same.

The second motivation for starting a business is to create your own job. The focus is to quickly realize revenue to generate personal income. The company has no real value apart from your work but it does keep food on the table. In this case, you start with an inventory of your own skills and abilities, and match them up with market needs that will result in sufficient revenue to meet your needs.

I can totally empathize with your situation. I am not too far behind you and had a difficult time returning to my profession due to age and perceptions of stage of life.

If I can be of any further assistance, let me know.

The worst motivation for starting a business is the need for income. A business has to be built over time based on meeting a market need. Of course a business must make money to be successful, but this can take a bit of time.

So, the real need is to use the online world to make money. Based on your copywriter skills, here are some ideas to get you started:

1) Start a blog. You can do this for free with platforms such as Blogger and WordPress. This will provide you a chance to show case your writing talent. Writing articles about copywriting can both demonstrate your writing ability and be used to market your approach.

2) Join job markets. There are several freelance sites you can use to make extra money without little to no cost, such as Upwork and elance. You will find jobs on these that will help you earn money and build your portfolio. The pay can be low as the markets tend to be aggressive but a few good contacts can lead to a better source of work.

3) Build your network. Connect with people who provide web marketing services. They need guest bloggers, ghost writers and ad copywriters. Over time you can build a steady source of freelance work.

Once you have a good portfolio and practice, you should consider building a branded web site. But first, build your freelance brand. This approach works with other skills too.

Let me know how else I can help.

First of all, finding keywords that are relevant to your products or services is the first step in an SEO effort. If the words are not under high demand for advertisements, the keywords can be more cost effective as long as there is still sufficient search volume. In other words, you want to make sure they keywords are something people use.

The next step is a solid content strategy to employ the keywords in a natural way. I find the SEO Table at search engine land to be the best guide. You can find it at http://searchengineland.com/seotable. The key is to use the good practices, such as incorporating words in your articles and posts as well as URLs, and capitalizing on external sources, such as Social Media. At the same time, you artificially loading up on keyboards.

In our area, we have several different incubators which are also an excellent place to find advisors. I have also used Meetups to network with people with similar interests in both my field and markets.