Everything Eli said is spot on. Optimize your on-page and create compelling and valuable content on a regular basis focused on your customers/prospects and the links and PA/DA will follow.

We use some industrial directories such as ThomasNet, MacRAE's and GlobalSpec. These directories do provide some, but decreasing value over the years. Google (according to Matt Cutts) looks at a few items when assessing these directories:

• Editorial discretion (who can and can't get in)
• Value (original and informative content)
• How much work they do on the site
• Usability

A good rule of thumb-if the directory looks outdated, lacks original content, has broad content (not in all cases but niche is better), looks spammy, has poor usability and anyone can get in don't use.

H1 should be the main heading and reflect the landing page. It should also be unique to the site (in most cases). H2's should be subheadings, H3's sub-sub headings and so on.

Do keyword/competitor research and create compelling content that is great link bait. Inbound links will organically occur if the content is useful. Repeat this many times and traffic will increase for these landing pages and push your DA up. It's difficult, and requires much times/resources. This is a better route than buying links that can get you hurt you in the future. Good luck!

Good way from => http://www.henderson.cc/wp/tag/301-redirect/

While poking around on the Web, I found an article by John Honeck, entitled “Page by Page redirects in IIS for .asp, .html, .pdf, etc.“. He presented an ingenious method for implementing redirection of a PDF document. Rename or remove the old PDF document from the directory. In its place, create a new folder and give it the exact same name as the outdated PDF, including the use of the .pdf extension.

Inside the new folder, place a default Web page (index.htm, default.htm, etc.). In the head of the default Web page, place meta redirect code. A user (or Google spider) visits the directory, finds an object with the correct name and the default Web page redirects them to the new content!

Here’s sample code:

<title>Moved to new URL: http://www.example.com/pdfs/thenewpdf.pdf</title>

This page has been moved to http://www.example.com/pdfs/thenewpdf.pdf

If your browser doesn’t redirect you to the new location please click here

Don't agree. Many time you have room for your company or branding and it is a good idea. It's an easy way to gain market awareness.  Also, stuffing a ton of kw's in a title can look spammy.

The way I always use them is if we didn't have a high organic position for one of our product lines, I would allocate points to get the no-follow link removed off the free listing. Did this help? I didn't notice any increase/decreases in organic positions for any competitive keywords (ie: widget). Did it help for long-tails (ie: stainless steel widget)? It seemed to help, but difficult to say.

Feel free to PM as I'm extremely familiar with their programs.

No evidence on this.

As long as the text and background isn't the same color you are safe. Also, the more contrast the better for usability sake.

Some questions to help you analyze:

• Was it an overall drop in traffic or for specific articles?

• Did you check your Google Search Console for any messages or did you analyze performance report or etc?

• Did you look to see any Google Algo Changes?

• Did you see any drop in Bing Organics?

• Any major site changes?

  Good luck!

A good rule of thumb is if you can see all the "hidden" content if Javascript is turned off you are basically safe.