Clients are clients, but clients are also pigs, cunning, excellent smooth-talkers who try to extract the most out of their bucks, sometimes understanding, generally and I mean most often stingy as hell. The point is not that you have talent and they have work, the point is you have talent that needs to be well paid and they never will.
Keep these like aces in your sleeves:
1. Value your work. 2. Don't undersell yourself.
3. At times, Learn to let go of work (Most Important)
Yes, sometimes letting projects go away and it being executed by someone else can reap its own benefits. If you value your work enough, at times you may just put down your feet and say 'No, sorry I won't be able to work under that budget'. And if you really are good at your work, skilled as hell that no one else is able to reproduce the exact same quality of work, then you will see the exact same client come to you after a few months and ask you to work on their next project since they chose someone based on lower budget and that didn't work out well for the brand at the end of the day.
I photograph food for a living, I live, eat, spend umpteen of hours meeting people, chefs, managers, marketing top-notches to understand the brand, the food and the experience. I also eat at these places, make a good rapport with the service staff, make sure to ask a few questions to the chefs or sometimes may be just talk to them and ask them how their day was. Indirectly or consequentially I learn about their belief in the food (or if not), learn about commitment to the work and also get to know them as a person, all of which helps you on the day of your work. The better you know them, the better you know who's good at plating, who's good at styling, who's in sync with you when you show them references of how you want the plate to look like. All this helps smoothen the work on that crucial day and you end up with some fantastic pictures of drool-worthy frozen yogurt in a waffle, dim-sums in a basket with steam rising just as you opened the lid or a simple yet elegantly stacked juicy tenderloin burger where the sauce is just about to drip and the cheese ever so perfectly melted.
Training:
Yes, that's what this post is more centred at. Nine out of ten times, you will be shown an unachievable reference of the end product desired by them, the task of which will carry a budget that can barely come close to producing something that looks or works half the reference. Now, I know the faces we all make and the things we say. "Sure, This is achievable", "Sure, This is achievable, but the budget is just not right enough" or "Sure, only for this one time I can do it in this budget, next time I won't be able to". Well, in all the three scenarios you may have the project in your pocket, but either you are making nothing, something or a little more than something. It's great, if you actually made something from it, but did you in turn ever give back anything to make your further work more smoother? Never did you ask questions, help them understand your work, efforts going into doing that work or for them to understand how long did it take you to acquire those skills that you are able to illustrate a logo in under an hour and which would have taken anyone else over six hours, leave apart the precision and the finesse of your work; Thus creating a one-time relation that barely any client or people of the organisation that worked with you on that project will value or remember you for, and maybe just when one of that influential person joins a new firm, chances are that one person who loved your approach actually remembered you and your work and went on to recommend your name to this task at the new firm. That's what I believe in - build long term relations with people, some may benefit you in your professional life while some may evolve out to be your drinking buddies or just very close friends.
Thus in my experience of working in these professional photo-shoots, I have made some great acquaintances who take care of me at work, feed me well, understand my subject (do not interfere on technical topics and leave it to my discretion), provide as much support on-location and lastly, make sure my invoices are processed at priorities, and some have even been such helpful beings that they have gone ahead to deposit cheques into my account, sent me screenshot of the deposit slip and done all this with a smile and zero nagging.
The crux is that treat people well, help them understand your work, value your creative slash technical side; and once you've secured the task, just make sure to kick-ass.