Ryan, inspired by Kim had the idea of a group writing project: If I Knew Then What I Know Now. Nice idea, should help a few others out; here is my spin, Internet related:

1. Great Firewall. I knew it wasn't 'great' in the positive sense before coming (September 2005), and had some idea BBC News and Google Image Search were blocked. Soon after arriving the potency of the Golden Shield became apparent - Wikipedia, Blogspot, Wordpress.com, to name just a few, were blocked, even Flickr last week. The sophistication has been increasing, with different access points apparently exposed to different levels of filtering. Firefox plugins and Tor have become the norm for many. If you've got a blog, or anything in fact, don't put it on a Blogspot account. Get a domain name and some cheap server space, more detail here. Since my arrival, Google Image Search has become unblocked (partially)! [On the morning of writing, some of Wikipedia, most notably en.wikipedia.org, became unblocked. zh.wikipedia.org remains blocked.]

2. Connection speeds to the rest of the world (anywhere outside mainland China) are slow. Connections between computers within mainland China are really fast - on demand video streaming is not a problem in most urban areas. Communication with computers further abroad is a more arduous task. Hong Kong is the fastest outside mainland China (and outside the very tight legal regulations imposed on websites within China), North America is slow, Europe is very slow. Still fast enough for Skype.

3. DVD shopping. Why buy fake DVDs for 5RMB? The somewhat more easily shutdown-able (should the authorities want to do so) YouTube clones provide full movies and TV series for free! More on this here.

4. I have found the China blogosphere undeniably the fastest and highest quality source of English language reporting on China. I still read some newspaper columns (via RSS) but blogs have become my bread-and-butter for staying informed about the many niches of Chinese culture, life, economy, politics, food, anything. I found them such an effective medium, I am a partner in a group-blog project for my current city of occupancy, Dalian. There are plenty of high quality blogs out there, I started finding them via the China Blog List, but found it clumsy. Chinalyst and the Hao Hao Report are recommended as starting points for some great reporting.

5. The government have a plan for the Internet. Like most things in China, it is not an organic process to evolve freely yet easily inter-operate, it is a system which can be monopolised for commercial and political motivations. The Central Government is actively involved with regulation of the Internet. Bear this in mind when considering a China-centric Internet venture. The government seem much more lenient with the English language Internet, than the Chinese language segment, for now.

Bonus: Learning Chinese takes time and dedication. Don't work part time and study part time, it's too easy to find distractions. If you want to study Chinese, enroll full-time. For most career paths, it will quickly pay off.