You will only make a profit from your Helium articles if you attract traffic and gain readers. There are two primary sources of traffic, that from search engines, and that from the social bookmarking sites. Of these, the traffic from search engines is the more valuable, as people referred from the search engines are more likely to click on ads. Search engine traffic also tends to be steady and reliable - as long as your article features well in the results, you will get a steady stream of traffic, whereas traffic from the social bookmarking sites tends to be short-lived spikes.
The key to getting traffic from the search engines is keywords and back-links. Keywords are the words or phrases the user types in the search engine. You need to ensure that these are in the title and body of your piece. The best way to ensure that your article contains most of the keywords naturally, is to write long articles (at least 600 words) which are detailed and informative. Also be careful with your use of language. Newspapers might be able to use catchy, funny or slang words in their prose to give it pep, but people don't actually type slang or puns into search engines. Instead they type exactly what they are looking for. For instance Google Insights for Search shows that practically no one is searching for the phrase "property meltdown", which is a popular tabloid headline. However there is a lot of interest in the phrase "property prices falling". Writing online articles requires a different style from writing for the print media. Do take care not to pack your article with too many keywords - Google considers any article with more than 12-24% of the content being keywords to be spam.
Your article acquires back-links when other sites link to you. Consider setting up a lens with Squidoo, that has links to your article. Link to your articles from your blog, put the URL to one of your articles in your signature when you post on forums. Social bookmarking sites are useful in that having your article bookmarked on the site provides you with back-links. There are literally hundreds of social bookmarking sites out there - Mixx, Newsvine, Post-on-Fire, Furl, Fark, Propeller, Thoof, Delicious, StumbleUpon, Digg, Reddit. Try to ensure you have a presence in all of them (that way you accrue more back-links, and an interested reader may discover your article and give you a natural link in their blog). Most social bookmarking sites forbid self-promotion, so try to get someone else to submit your articles for you. If you must do it yourself, be discreet, and don't spam. Only submit one article of yours for ten articles you submit that are not yours. You may get a little traffic from these bookmarking sites too as a pleasant side-effect.
You can check how many back links your article has by using one of the free back-link checkers on the web (Google to find them). The more back-links you acquire, the more likely that your article will earn a pagerank in it's own right, which in turn will help ensure it features on the first or second pages of the search results.