I’m a fan of jQuery because it promotes unobtrusive markup and functionality and has a wealth of plugins to take care of common web development/ajax functionality. Marc Grabanski offers some tips for working with it effectively. I’ll need to look at livequery in some apps I’ve put together. If you need to attach events to elements, and re-attach the same events when parts of the page are updated, it should make keeping track of it all a lot easier. My tip for working with jQuery? Use Firefox with Firebug to inspect the page and debug ajax requests.
I’ve been coding using jQuery since shortly after it came out, and well — I’ve been using it almost every work day. Here is a few tips that have saved me time.