Try article marketing - it can work pretty well. Write an excellent article about related topic and submit it to some quality article directories. You will get targeted traffic and some backlinks which will help you to get higher in search engines.

Submit sites to different directories and promote through forums, blog, social networking sites, classified sites ect.

I would say paying some $$ in some GOOD directories worth a lot. I would say those will help to promote and get more revenue and traffic.

Use other bid directories and directories catalogs.

I don't think directories can generate that much traffic to earn good revenues, you need to implement many things such as social media optimization to get more targeted traffic.

article marketing is the only way related to your work

With the kind of services you are offering, there is huge potential of customers and traffic. You just have to keep your basics right all the time. Usually we only focus on big things and forget the basics. Points to remember are:

1. Ensure that you act on your customer's feedback immediatly.
2. Always respond to your customers in time. This keeps confidence and they spread good words about ur site.
3. Submit to as many free directories as possible.
4. Keep improving the look and feel of your site, it always adds freshness.
5. Main focus should be to ensure that your existing visitors keep visiting you.
6. Write about your services and your site as much as possible at whatever place you may find, i.e. press releases, blogs, forums etc.
7. Submit your site to as many social bookmarking sites as possible. This is a trend thats catching up real fast and is giving pretty cool results.

I hope you will be able to gain some good quality traffic to your site.