Here's a little secret that comes directly off #1. Usually when people don't pay your fees, there's a reason. Maybe they can't afford it, but more likely they aren't satisfied. If you sue them for your fee, and they get "their day in court," what do you suppose they're going to do?
Countersuing for malpractice is the most common way of trying to get out of paying a fee. You may find that the accumulated aggravation, not to mention the increase in your malpractice insurance premiums, makes it not worth it to chase a fee. You probably will, actually, once it happens to you. Avoid all the aggravation by just reaching out to your clients and seeing if you can fix whatever it is that is bothering them. Maybe you can, maybe you can't, but at least you put forth the effort.
Of course, there are a couple of exceptions. If you are being sued directly for malpractice, it makes sense to tack on a counterclaim for fees. Also, if the amount in question is "big" (whatever that means in your situation) and you're willing to take the chance that there will be additional litigation, go for it and sue for fees. Just understand what it is you're getting into, and what the potential consequences are.
Just a note for litigants: this is not an invitation to skip out on paying your fees. If you don't pay, and there isn't a very good reason for it, sooner or later you will be dragged into court and a Judge will most likely throw the book at you.