Don’t worry, Google bans are not as common as you think. However, if you are doing some things that may run close to the wire, then this video from Matt Cutts may help you do what you need to do.
In essence, if you don’t play by Google’s rules, then Google will get you in the end. If you are in your business for the long term then, it makes sense to plan your SEO over the long term too. Google will NEVER stop being attracted by great links and great on-topic content. Anything else is up for debate (no matter what your SEO guru tells you…).