1) Your loyalty belongs to your company. Always do what is best for your company.
2) Always share your knowledge freely.
3) Never strategize in order to "secure your job".
4) Always pick the project or job where you will learn the most (grow the most as a person).
I would guess 90% of people I have met ignore this and start strategizing at some point. They seem to always lose in the long run.
"The company treated me wrong, so why should I work as efficient as I can?"
"I can't teach him EVERYTHING or my job won't be as important/secure any more."
"I will pick this project, because I have done something similiar already, so it will be easy work."
When sticking to 1-4, relevant people will notice eventually and your trajectory will go up.
When ignoring points 1-4, relevant people will lose respect for you. And even worse, you will lose respect for yourself.
This is just my opinion or my experience so far.