How can you put yourself in a position to earn more generous rewards and gain more flexible work conditions?
Step one. Make sure that in your working relationship with every boss, you understand how to meet the basic expectations of the job and how to go above and beyond - and what rewards might be available.
Step two. Build working relationships of trust and confidence with every boss, through open communication and transparency so that you know exactly what you have to do to earn more - no matter how great or small those rewards might be. Help every boss monitor and measure and document your performance every step of the way. Don't be a big baby when it comes to acknowledging the fact that you may NOT have achieved the necessary goal to earn a particular reward. Likewise, don't be too greedy when you do achieve the necessary goal and it comes to collecting the promised rewards.
If you make a commitment to the boss, deliver on your commitment. If you fail to meet a commitment, be honest and forthright about it. Ideally, you want to put your boss in a position to let you know whether your work is hitting the target on an ongoing basis. If your boss can't deliver on a reward right away, or if a promised reward somehow evaporates, try to be understanding. Try to write off the loss as a cost of doing business and an investment in the account balance of that working relationship. You might not always get the reward right away, but you won't have to spend time wondering if your performance has been noted and appreciated. Use the appreciation to gather momentum.
By the way, if your boss can't reward you right away, but seems to appreciate what you've done, consider asking for a written commendation. Maybe your boss could just write a letter describing your success and give you a copy, place a copy in your employee file, and pass a copy up the line to your boss's boss. That's a good way to help your boss make you feel rewarded rather than jilted in the event a hoped-for reward falls through.
Remember: Your boss may not realize how much power she/he has to influence your rewards. Sometimes your boss has discretionary resources available for rewards, and just doesn't use them. Sometimes your boss has more power to influence senior management regarding your rewards, and just doesn't use it. Sometimes your boss could bend over backwards and jump through hoops to get you more rewards, and just doesn't do that. That doesn't mean you should be pressuring your boss for more rewards all the time. Rather, it means you need to make it obvious to your boss that you deserve more rewards. And you need to make it easier for your boss to give you more of whatever discretionary resources, power, and effort are at his/her disposal. Help your boss reward you.