> Just ask, in advance. If you're a valuable employee
That is a massive, massive if.
You might as well recommend fighting over your gym membership contract, of a bank contract, or a telecom operator contract. Right, it's your free choice, uh-huh. Either you accept it as is, or you go fuck yourself and workout at home, without internet, looking for a job where you'll be paid in cash (which also is far from being common). Again, unless you are preemptively perceived to be a very special customer (i.e. "expected to bring in a lot of money"), in which case your contract probably isn't typical to start with. And it is most likely your lawyer who negotiates over it for you anyway.
The only contracts you can't negotiate are government job contracts and union jobs. Which is one reason I'm not interested in either of those job categories.
> bank contract
Haha, I once negotiated a large loan from my bank at an interest a full percent below their official floor. I'm not even very good at negotiating, some people I know are much better.
> telecom contract
Have you ever said the magic words: "that sounds high, can I get this for a lower price?" The salesmen are allowed to negotiate. The initial price they quote you is the sucker price.
Every time I've been to the dealer for car work, all I have to do is balk at the quote and 10% comes right off.
This is not a special skill. Anybody can do it. Fer gosh's sake, you're expected to negotiate.
I haven't had success with trying to negotiate telecom contracts. When I balked at the price, the salesman would sometimes offer a contract with lower levels of services along with the price reduction. And typically, it's more costly per unit of service, so not much of a bargain.