Branching and Merging Strategies

I have been tasked with coming up with a strategy for branching, merging and releasing over the next 6 months.

The complication comes from the fact the we will be running multiple projects all with different code changes and different release dates but approximately the same development start dates.

At present we are using VSS for code management, but are aware that it will probably cause some issues and will be migrating to TFS before new development starts.

What strategies should I be employing and what things should I be considering before setting a plan down?

Sorry if this is vague, feel free to ask questions and I will update with more information if required.

This is the single best source control pattern that I have come across. It emphasizes the importance of leaving the trunk free of any junk (no junk in the trunk). Development should be done in development branches, and regular merges (after the code has been tested) should be made back into the trunk (Pic 1), but the model also allows for source to be patched while still under development (Pic 2). I definitely recommend reading the post in its entirety, to completely understand.

     Pic 1

     Pic 2

Edit: The pictures are definitely confusing without words. I could explain, but I would basically be copying the original author. Having said that, I probably should have selected a better picture to describe the merge process, so hopefully this helps. I'd still recommend reading the post, however: