Jakob Nielsen's 10 general principles for interaction design. They are called "heuristics" because they are broad rules of thumb and not specific usability guidelines.
Picking a font size for the web used to be really easy. 16 points and you’re done. You could feel confident that your content would be decently readable on PC or Mac, Netscape or IE. Man, have times changed.
Typography
What's the Best Font Size For the web? Well, It Depends… — Imarc
Knowledge
How to Write Proposals that Win 80% of Deals — The Startup
If you want high-ticket clients, proposals make or break your business. Learn how to write a winner. Most of the time, people don't believe me when I tell them that it's 100% possible to close 80% (or more) of the deals you write proposals for.
Proposal
How to Write Proposals that Win 80% of Deals — The Startup