Be seriously reliable
Reliability isn’t just about showing up on time. It’s about being there when things get tough, so helping out in a difficult situation will show that you’re more reliable than the average employee. That said, you shouldn’t feel that you are being taken advantage of so select opportunities to shine when it really counts.
Make your boss’ job easier
If you’re making your boss' job easier, then he/she is likely to fight to keep you if it was ever in debate. Having someone influential on your side at work is very important. If they see you as a person who makes their job easier and makes their team look good, they’ll be on your side. Try and find a gap in skills so that there are things you can do that your boss can’t. The more heavily your boss relies on you, the more indispensable you become.