"Back yourself into a coner - Nothing makes asking for more money easier than not having an alternative."
Maybe that makes the conversation more urgent and steels your nerves. I could see how there'd be a psychological benefit there. But the best way to build leverage in a negotiation is to have a strong hand before starting the negotiation. This concept is known in behavioral sciences and business theory as BATNA ("best alternative to a negotiated agreement"). In layman's terms, it's your Plans B, C, D, etc. The stronger your backup options, the better your position in the discussion.
This correlates with the market-based theory discussed in the article ("If you can find someone to pay you X, you're worth X"). You increase your chances of getting X if you can get Backup Y as close to X as possible.
Glassdoor is extremely helpful for leveling a lot of the information asymmetries that push a money discussion in the employer's or client's favor. But Glassdoor isn't the same as leverage. Just because a typical Role X makes $Y doesn't mean you are entitled to that...unless you convince the market that you should be, i.e., by getting someone to give you that much (or more).
When I was working as a consultant I literally doubled my rates in the space of two years by simply not caring if I lost any gigs because of it and that was staring with a hourly rate of 3 figures.
At the time I was following the advice I had picked up from other consultants - never leave money on the table. I had enough money in the bank to retire indefinitely, but instead of simply walking away my aim was take as big a cut of the pile as I could get it.
Five years later I was sick as hell of the work, so I did walk away but the opportunities in that niche were rapidly fading by that point. There was probably less than a year's worth of work left anyway.
At the end of the day, whatever works best for someone works best for him. I would just caution against intentionally backing oneself into a corner. Sometimes we do our best with our backs against the wall, but that doesn't mean we should seek to put ourselves in that position.
I think there's an advantage to this though.
> I’ve done plenty of business with friends. In fact, the
> majority of my business has been with friends or
> acquaintances. Some of those friends even stopped using
> me when I raised rates over the years and they’re still
> my friends. I’m having drinks with one of them tonight,
> in fact.