However, I am no pushover either. I am all for tit for tat. I don't manipulate you but you don't manipulate me or take advantage of me. I am fair by default as long as I am treated fairly. This is the general gist of my approach to the workplace. Not sure this is best. If you are anything like me..
Do you have any experience in this matter of manipulation at the workplace? What did you learn hard way? What is your defense system now?
Nip issues in the bud. Otherwise they just grow. Often they multiply. Escalate to authority figures where they exist.
How you deal with problems depends on how bad it is. If it's really bad, you'll probably have no choice but leave. With the caveat that there is no ideal place out there, you can always try starting your own.
Otherwise, the best strategy I think is to let your skills speak for themselves, get things done and be so good (or good enough) that they can't ignore you. They don't have to you like you but they should respect you for getting things done and being invaluable.
And then there is always the option of talking to your manager or HR if the problem is serious enough. HR isn't necessarily your friend but it's in their best interest to keep good people to protect the company so they should be able to help in case of serious faul play.
Be generous to everyone except the manipulative. It's a little "manipulative" because the generous ones will give you more than you gave them. But it also identifies the impostors.
Manipulative people are often lazy, so make it painful for them.
Put up a fight if you're in a bad spot. Treat it as a war, with an actual battle plan and allocate resources to win. End it quick.
Don't hold grudges. You can become friends with former enemies. But bear in mind that a dishonest person will stay dishonest, even if you marry them.
If the situation is too bad, change your environment. Plenty of companies, especially in tech, who are happy to treat you well and want to see you happy.
Context: my career went dev (not long) to consulting to product (most time) to executive management (current).
Your best effort at what? A few years ago if I had said that I would mean I want to do my best at imposing my idea of good code and products on the company. I've recently given up the fight and now give "my best effort" towards being pleasant to work with, helping others, kissing ass, doing bullshit, and almost never working overtime and standing up for myself when it's time to go home. I'm happier now.
And what I used to consider kissing ass or doing bullshit I now consider to be selling myself to the people who pay me and just doing the work they pay me to do.
I do still push for changes I think would be good, but much less aggressively.
I have no advice for you. I'm 9 years in with a masters and I'm only a midlevel developer with no future.