These are classic project management challenges, and there are many ways to approach them. But, here are some high-level thoughts:
If a client makes changes that substantially effect the cost of delivering a project, you should charge them for it, yes. You need to do it in a very organized way, with a written change order and good communications so that the client is always clear on what/why/when they are being charged.
If a client insists on a fixed-bid, but cannot commit to a project scope then just break the project into the smallest piece that they CAN commit to and bid on that.
Make this the clients problem, by having a single point-of-contact on the client side and getting that in writing. That way, they can bicker on their end but you know who to listen to.
Sagewing’s is good, and the emphasis should be to get it in writing. Even if everyone is acting in good faith, there is too much room for misunderstanding if any of those key provisions are simply oral. Even written contracts can be unclear and subject to misinterpretation (which can be seen by the number of contract disputes that end up in court) but a written contract is much less likely to create huge misunderstandings.
Obviously, though, continuing close communication with the client throughout the project is a key to avoiding surprises (and disputes).
Client keeps coming back with changes beyond the scope of the project. Do you charge them more? Or do the work to keep them happy?
Build fat into the project costs to account for this. After a few projects you’ll get a feel for what is normal. It can’t be avoided as much as you would like to. It’s just too hard to go back to people and charge them for post design changes. A lot of people need to interact with something before they really know if they like it. If they are exceptionally painful then don’t work with them again (finish the project but move on). After a few projects some clients might be agreeable to working hourly.
Planning and pricing for a client project that is very open ended yet they want a fixed price quote - What do you do?
Do a full scope up front, charge them for this privilege unless most of your projects are like this (in which case build more fat into every quote). Or if you can’t pinn them down to a scope then offer hourly service only. If they won’t agree to that there’s no fit, move on.
Clients that have many parties involved and conflicting opinions leading to budget blowouts, any nightmare scenarios?
Ha um yeah. Couldn’t be bothered going into them but every web design company owner will have horror stories, the methods above were the only ways I could manage it and also by pre-qualifying your leads better. I used to try to scare the bad ones off as much as possible.