What's the difference between nagging employers and staying in touch?

I often wonder at this scenario as, so far, I haven't found a solution in any Freelance Writing handbooks as of yet. I wonder, what's the difference between checking up on an employer after they say they would like to work with you and then take several days to get back to you or checking up on an employer the next day? One is maybe more polite than the other, I would assume waiting for several days the better advantage, but by then the employer has probably forgotten your services so better to nag them quickly right? In the advertising world it's always good to be in your face, but is that true for a home business freelance writer?

Being too eager could set them off, make them feel like you NEED their services in which case they loose respect for your business because you obviously must be falsely advertising if you need the work so badly. Also, giving them time means they can better organize their plans for you and your job won't seem as rushed or conflicted. Everything will be ironed out, clearly stated in a contract and good to go for a great tip top job. But where is the line of contact for that kind of service? When does etiquette end and bad behavior begin?

I've had several clients where I have had to haggle them to get anything out of them and get paid at all. Some of them said they needed everything right away and then declined to give me anything to work with or any picture of the project until much later. I often felt like dropping them except in this line of work you can't really afford to drop a job when your starting out. So, I persisted, eventually got paid the sum I was supposed, but still had to hassle them every six days to give me a new assignment. Now this has made me nervous for all my other assignments and I just received a new one where a man got in contact with me about a website. We negotiated the whole deal and he said he would send me a project plan and fill out a statement with his signature. Before he was supposed to send it, he sent another email saying he would check with his consultants and get back to me tomorrow. Well, it's tomorrow, do I bug him?