I'm sure that many forums have this same topic, but it seems like a great way to get a conversation going - and provide some useful info at the same time.
Here are my top 5 tips for new residents:
1) Use the Alt-Zoom feature to move your camera. I think that this is THE best way to look around SL. The camera movement dialog box is just too clunky and moving the camera with just your keyboard is a bummer. Here's what you do:
Hold down the ALT key (OPTION key on Mac keyboards) and move your mouse around. Now you can zoom in and out and rotate around the point that you clicked and get a better view of your surrounds. Other options are enabled if you hold down ALT+CTRL (OPTION+Command on Mac), or ALT+SHIFT as well.
2) Explore the building tools. One of the greatest things about SL is that everything you see was built by another resident. Get in their and rez some prims and start experimenting. If you need some help you can attend some free classes in-world or visit one of many places that offer tutorials and info. Try the Ivory Tower of Primitives, or New Citizens, Inc.
3) Attend a live music event. There are live concerts and DJ's performing every day in Second Life. Great fun and the perfect place to meet some people in a casual environment.
4) Get some freebie items. SL can be quite confusing at first glance and it's hard to know what to do or what can be created with the tools that are availble. There are lots of free, or nearly free, items that you can grab for a bit of fun and experimentation. Try The Gnubie Store or Yadni's Junkyard.
5) Ask questions. It can be a bit scary to talk to strangers that you meet in-world, but there are many very friendly, helpful people on the grid. More often then not people will be glad to help you out. We were all newbies once. :)