I clean out my DCBackUp leaving the ccmerged file as is. I also clean out the temp files from the DCCache file. I also clear out the CASPartCache, compositorCache, scriptcache, simsCompositorCache and the SocialCache every time I start up my game as well as getting getting of the FeaturedItems folder. I know there is a way to keep the featureitems folder from showing up in the TS3 folder but I haven't yet tried it.
@igazor might know more of what needs to be done besides what all I do in my folder... :)
And it's best to "Save as" when saving a game so that you have an earlier save to revert back to in case your current game crashes. I try to save when I'm done something such as decorate my lot or at the end of a Sims day or when a Sim had leveled up a skill or 2... :)