Few tips:
- "Give you tight deadlines". Doesn't work that way. YOU are the one who will give them an estimate and a timeline based on their requirements. Sorry but don't get forced into delivering something quick because you want to please the client. You will always lose. Never agree to an aggressive timeline. Whatever you think is reasonable, multiply by 3 before agreeing with the client.
- Tell the client that timelines can shift if they change scope. Some things just take time.
- Remember that some people just have the habit of making everything urgent. In many cases, they don't really mean it. But it depends on the person. If everything is urgent, nothing is urgent. Challenge them on it if needed.
- Always under promise and over deliver if possible. It is better to say "3 months for this project" and deliver in "2.5 months" than "Yes I can finish in 3 weeks" and then you are nowhere near it in 3 weeks.
- If client keeps asking to deliver quickly, remind them of the timeline that was agreed mutually.
- At the end of the day, it is 1 client. If they are becoming a nuisance, drop them. Beauty of freelance and being your own boss. Don't let a client boss you around. Find another one.
Receiving pressure on a constant basis takes a toll on mental health, and health is our most precious asset. Don’t waste it with people who are not worth it!
Here’s an argument to convince you: your client is not creating the kind of environment where you will produce high quality work or grow much as a professional. He’s creating the kind of environment where you will just ‘get stuff done’, lose your passion and be miserable in the long term.
If you'd like to fix the relationship rather than to break it, my recommendation is to learn negotiation skills. They're very useful for life in general, so it's worth investing time in learning them.
There are reams of books, webs, podcasts, videos, etc. about the art of negotiation so you can start by the type of content that suits you best.
After you learn sufficient negotiation skills, I suggest you use them with your difficult client and see what comes out. Maybe he or she stops being a bully. You know, sometimes people are abusive just because they can get away with it. The moment they see strong pushback or confrontation they typically flee to find the next (poor) victim.
To your examples, I would reply something like:
"I need your help to wrap this up ASAP" Sure, let me have a look at my to-do list and I'll get back to you with a delivery date ASAP (then, calculate a date that already includes a safety buffer and negotiate with the client)
"I am under a lot of pressure and time constraint" I understand and I empathise with you, but I also have a lot going on and I don't want to promise you something I can't deliver. Can we please go over the scope and activities together to put realistic timings on them?
Tactics: - show the other person you're on his/her camp - explain that it's not reasonable to commit to dates that can't be met. Bonus points if done with confidence. - expose the risk they're creating by committing to something that is not reasonable - position the discussion as win / win... you need to review dates for your client's own good (what would his or her boss say after deadlines are not met?)
If you choose to retain the client, retrain him or you. You know the client, yourself, and the situation far better than we do. Will an email with an excerpt from the contract quiet him down? What about responding with "It will be done when it's done" or "You are one of my clients. If you want me to work only for you, you will have to pay me much more."?
It is up to you to decide if you can allow the pressure to roll off your back or not - I'm guessing you have a hard time with that based on your post. That is a useful trait to cultivate, perhaps you can use this client for that until he decides to search for someone less learned in the art, someone who will jump when he demands.
Edit: Formatting
It's a tough one to learn, since you want to demonstrate how fast you are and usually the thing the client wants is indeed a five minute fix. But the reality is that the client will only appreciate the "quick turnaround" part as a novelty for a little while before it just becomes his expectation that you'll always be sitting at the ready to turn his requests around instantly. It can be really hard to walk that back after the fact.
Instead, when he asks for that next quick thing, "have a look at your schedule" and report that you can "probably break off some time early next week". Now, chances are that's complete fiction and you could just as easily break off the entire rest of this week as well as all of next month because this is your only client. But still, get in the habit of saying it if only to avoid this trap.
One day, with luck, you really will have trouble breaking off time for clients with less than a month's notice.
I suspect that it will not be quite so urgent after all. If it still is, that's great, you're prepared and can focus on the work. Your other clients will respect that you took on a rush job. Watch out for any deadlines you've already promised! Some should not be changed, you know your clients better than we do.
As for negotiation tactics, I find that if I listen more and talk less I learn a lot from the client. Ask questions, take notes, show them you're serious. Don't let yourself be bowled over by their panic mode. Learn to say No. Learn to say I don't know.
But in the end not all clients are worth keeping.
Seriously, that's one of the levers you have. Tell the client that your rate is now $CURRATE * 1.5.
Either you make more money or you lose the client.
Yes, increasing your rates is always risky; they might find another developer. But he doesn't seem like a great client either.