I've found the same thing. On occasion, I'll waive the 50% upfront deposit (or reduce it dramatically). I also don't have any penalty terms; they're a waste of

I've found the same thing. On occasion, I'll waive the 50% upfront deposit (or reduce it dramatically). I also don't have any penalty terms; they're a waste of time. If a client is not going to pay on time, they're certainly not going to pay the penalty %age if and when they do pay. Weekly communication is key. And, if you do end up with a client who won't pay, or consistently pays >30days late, you're better off without them. Fire them, politely, and explain why - then move on. There's no need to punish them - there is a great need to get the hell away from them.