(Standard Pins) - Basic requirements of good content marketing
Size: 2:3 Aspect ratio - 1000 x 1500 pixels would be the goal
Search Property: Title up to 100 characters (Keeping it under 60 characters would be suitable for Google SEO) - Up to 500 characters in Description (Absolutely use all your space but don't overkill with KW placement)
Link Building: Include a link to similar content on your website. You also can test linking to other content on Pinterest and A/B Test the performance.
Board Pinning: Include your new pins in clear, descriptive, and categorized Boards. You can convert every Reach into a sizable amount of Impressions with Boards.
Performance Boosters: Using written copy on the picture could help greatly (since Pinterest Titles are not really seen. Posting "Pin Albums" could help with time spent on every pin.
(Video Pins) - Basic requirements of good content marketing
Be FAST: You have to capture the viewer's attention real fast. So use copy and a fast intro for your Video Pins.
Time: Pinterest says between 15 seconds to 1 minute long could be good. Based on experience, 30 seconds would be the sweet spot.
No Sound: some viewers don't play videos with the sound on. So the video should be descriptive and engaging even without the sound.
Performance Boosters: Like standard pins, put a copy on the thumb image, use Title and Description and save it to Boards.