Assuming you just closed with the new client...
1) Research competition and assess what the top players are doing and categorize the main elements you need to have on the site
2) Research industry in-depth from the perspective of a potential buyer and compile key points to emphasize on the site.
3) One major thing that helps so much is various trade related logos and icons, NOT like BBB (which is meaningless), but actual certifications/trade related stuff for that industry. For example if there is a ISO recognized for that industry, make sure to include a logo of it and others on the homepage
4) Start with building a simple site, 5 pages no more. You can expand as the operation rolls out.
5) Take all the research you have done and get compelling content written that demonstrates competence, knowledge and expertise in the industry
6) Include some pictures preferably of people who reasonably look like normal people and not models, with testimonials etc...
7) I find having a rotating slider above the fold (meaninng on the page when someone first goes to the site) helps to get more content in front of the visitor before they scroll down or leave the site...
8) Try to gear your content towards proving to the visitor/prospect that you understand exactly what they need and can deliver.
9) if you can include a free offer or something to push people to call/fill out form do it.
10) Setup all conversion tracking and goals
11) Expand site with more landing pages made as specific as possible. If you can take 1 service, and turn it into 10 landing pages from all the various perspectives a potential client would think, you will find much higher conversion rates
12) Tweak as needed.
About getting traffic that is up to research and figuring out best ways to reach potential prospects for each industry.
Main thing is to learn and research the industry well and have solid sales points down cold. Then putting that research into action with a clear and easy to view website that must look good also.
No question we see the results flying in!!
I think the major factor in a big success is how well the sales points were researched and how well you can communicate with the potential prospect that you are the ones they are looking for. Get that down and you will always have success.