First, know things and people are worth what others will pay for them
As a floor, you need to fund a modest life, and that means retirement, healthcare, personal improvemwnt, food, home, etc...
Add some small margin onto that for quality of life.
Second, get business minded. It helps to take an interest in the company, know it's financials, and it's goals. This helps you position your value in direct, meaningful terms.
I very strongly agree with being ready to walk when it comes time for salary discussions. If you can't walk, you will get the lowest comp, unless you have some relationship or other leverage to play on.
The bigger the increase, the more this matters.
The idea that you are as valuable as a replacement and training is false. This ignores you as a person, relationships you have, etc... this is often the framing, but do not be afraid to expand the discussion.
Set goals and justify them. This is something sales people do all the time. They are motivated by those goals and communicate them easily and consistently.
Ie: I need 200k this year to fund my travel and home investment plans.
A tech person may have identical goals, or maybe is wanting to build something, or send a kid to school.
Value these and frame your motivation to work in terms of your goals, company, love of the work, etc... Managers, and higher level people in the company understand and respect goal oriented people. Make sure your goals and the company align, or make basic sense and there are no conflicts.
This all speaks to the work being worth it and it also speaks to reasonable expectations as opposed to just greed. Greed isn't bad. Clear, meaningful goals are easier to sell and for others to identify with. When others identify with your life purposes, they can value them and very easily see how you are inclined to stay and work for them. They also nicely dodge the "how much is enough?" Type questions.
Get your other offers and or secure relationships needed to know you can land on your feet should you need to make a change.
Be flexible. The company isn't seeing it's goals play out all at once, and you won't either, but there should be a path to get there that is realistic.
All of this boils down to a "this is where I need to be and why it matters" conversation.
Shared and aligned goals is a great basis for a loyalty type arrangement. People will work hard for others who take care of them and seeing that play out is worth a lot.
Another advantage of goals is there sometimes is more than one way to get there besides cash. Nice to have options on the table.
If it goes well, great. If not, you have your fall back.
You may be able to contract too. Where a company really cannot pay you what you need to realize your goals, perhaps a more flexible arrangement can leave you empowered to do it your self.
This does not need to be a conflict of interest, particularly where you may have more skills not being used, or relationships where you can add value in atomic, easy to execute ways.
Another consideration is involvement with sales and marketing. If you can take some risk, you may find opportunities to capture nice rewards by being part of that process. This takes some people skills, but getting them is worth it.
Ask sales how valuable a tech person who can handle and understand the sales process is. They could be your most potent value advocates.
You help them close a big one, and it directly benefits them. You leaving will present an opportunity cost they will have zero problem justifying.
Of course there are spiffs and such potentially mixed up in this and it all depends on who you are. Taking some risk will differentiate you from other techs and that can be worth a lot.
The first time you walk it is hard. The first time you cultivate advocates is hard. The first time you take risk is hard, and the first time you get a nice increase is hard.
All worth it. Actually it all is as worth it as you think it is. And people count on those things being hard enough and not worth it enough to keep you inexpensive.
What is worth what? That is your primary question to answer. Sort your life goals out, value them, decide on risk and alternatives, and then proceed to have the dialog needed to get you there.
Once you start down this path, you do not stop. It becomes part of you and others will see that mindset and treat you accordingly.