Here is a little knowledge nugget that Jack and I picked up during our time at An Event Apart: Seattle (more on that to come). We learned about this handy little site called caniuse.com that was created by Alexis Deveria. The site lets you look up HTML5, CSS, JS API, SVG, etc. elements to see what their support is across browsers. Then you can assess.. Can I use that?
We are freshly back from the conference and I have already started using and benefiting from it. Give it a look and find out what you can use. (Turns out you can use the first-child pseudo-element in IE8!)