Search for more related keywords with higher search result and rank them as well. If the search data for main keywords is limited, then this is your only option. Or make some useful comments in populated related blogs and forums with signatures.

Use the keywords of same niche with higher search volume. Work for these keywords to rank better. This will help to generate traffic. Also participate in social networking, share your business products or urls with suitable contents.

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Use paid Ads to improve traffic or example Google Adwords. I think the 5 keywords you focused are not competitive in your niche, otherwise you could have get a good amount of traffic from 5 keywords listed in 1st page of google. Try to bid more competative keywords using Google Ad and check how traffic is improving.

Other one is participating in Social media and promoting contest or events based on your niche. Get help from a Adverting agency who have experience in Offline marketing and implement campaigns with the help of them.

Make sure the keyword which you are using have high search volume, that may give you more clicks, Also note that the site on # 1 gets more and more visit than a site at # 5 on page 1. So, push site to # 1 or 2 and try to find new keywords with high search volume and work on it (To find high search volume keyword you can use Google external tool)

You have to understand what your client really wants.

He does not want more traffic. he wants more customers!!!

Are his website(s) optimized for conversion?

Does he have clear calls to action?

Does he have a solid follow up system?

Expand on the keywords your already ranking.

Target double/triple SERP listing per keyword, you probably won't get them all (double/triple) but you'll get a few which will bring in more traffic.

On the SEO level: do another round of keyword research. Look for long tail keywords which are a good match for your site and are likely to bring some more search traffic. Also look into more difficult keywords than the ones you're currently ranking for.

Focus attracting direct traffic. Find relevant sites to place reviews, news coverage or banner ads for your client's sites.

Also check your competitors' backlink profiles. You'll find great ideas for relevant sites to network with.

Try this. Go to Google Alerts and set up an alert. Every time your target keyword is used, Google will notify you and send you the link where that post is located on a forum / blog. This has helped me to generate lots of targeted leads to my site and I also backlink my site every time I respond to a user's question.

If your clients wants double his traffics then web 2.0 creation is the best way to hit huge traffics on easiest way. Web 2.0 creation with totally unique and relevant articles is the best proposal. You will surely get huge traffics from web 2.0 creation. Try this and get better results.

you can do two things. one is searching for new keywords and rank them to get visitors. its a lengthy process and another is to find the platforms where these visitors participates. like forums and blogs then start posting quality post in those areas regularly with a signature. that will deliver a lot of visitors.

First of all your keywords matters. If your keyword are limited and you are hard working than your result will not bring you satisfaction you want. If you want that you need more real traffic. You need Hootsuite. Try that and learn it. Hope you will get better results.

Choose some new keywords for your client's site. But be aware now a days over seo is harmful for sites, it can cost your client's site.

I'm having the same problem with local seo results.

Yes you can use SMO for increasing traffic.Make a profile of your company and start following relevant people and viral your unique and genuine content on these sites and viral your company's updates regularly.You can use blogs and articles posting make a rss feed of your blog and submit it to high pr rss directories thus you can bring traffic on your site...
Thnx...

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You can demand unique content for his site and upload weekly basis and choose high volume keyword if he not given that then promote.

Go with social media submissions for getting traffic

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Wilson,

Have you tried the social media? its a great factor in terms of traffic.