One should take care of both on-page as well as off-page optimization of the website.
Before going into off-page factors I would suggest having quality content on your website.

The most important On-Page Optimization SEO Tips are:

• Optimized meta titles and descriptions
• Use Proper URL Structures
• Should have User-friendly navigation (breadcrumbs, user sitemaps)
• Optimized internal links
• Text Formatting (use of h1,h2,bold etc)
• Image optimization (image size, proper image names, use of ALT tag)
• Create top quality fresh content (This is always the most important SEO factor!)
• Add External links (no broken links or links to ‘bad’ sites)
• Decrease page loading time
• Give H1 tag to page Title
• Create robots.txt for website
• Add data highlighter

Also, you have to do some off-page activities as well to generate quality backlinks.
Here are some ways to generate quality backlinks which are still effective in the SEO world and are the best techniques for a B2B business:

• Submit Business Listings
• Submit on Classified sites (if offering products)
• Take part in Forums & Questions/Answers
• Blog Commenting (for branding)
• Guest Posting (for exposure and branding)
• Social Bookmarking
• Social Media Sharing
• Video sharing
• Use some coupons to attract users. (in case of ecommerce sites)
• Directory (only if have high DA n relevant to your niche)

Just start doing this, surely you will start getting results(traffic)