When your car starts making that strange noise or that check engine light comes on, we've mostly learned (sometimes the hard way), the longer we wait until we address it the more expensive it can become.
The same thing can happen with your Revit Projects if you don't pay attention to warning signs.
If your project starts showing signs of instability - views that crash when you attempt to open them up, performance slow-downs, etc., you may have some corruption building up. If caught early you can probably get rid of it with little or no damage to your project. If you wait too long - you might wind up with a project that is completely unusable, and worse, now that it's gone on for a few weeks, you have no valid backups either!
As soon as you notice any signs of instability there are some very simple actions you can take that will, in many cases, clean things up and keep the situation from escalating.
First, review your warnings. If you've been good little Reviteers, you shouldn't have too many built up. Resolve as many as you can. If you've been bad little Reviteers, you might have some work ahead of you... learn from that...
Second, perform some basic file maintenance - purge unused content. Perform an Audit. Compact the file. These are things that should be done on a regular basis anyway.
Now, does anybody want to buy a used 2001 Jeep Cherokee? It's got a brand new transfer case and rear differential...