There's no 100% way to make sure you're not getting RSI so you have to make sure to change position every once in a while
If you want to limit chances you are going to get RSI or something like that just take care to follow these simple rules:
1. Don't stay more than 2 hours in a row in front of your workstation. If you don't have to piss then just stand up, make two steps and sit down again
2. Every half an hour try to follow the line of your office' roof with your eyes. This obliges you to move a bunch of muscles at the same time, eyes, neck, jaw, et cetera
3. Have a mandatory break every maximum 4 hours. Don't lunch while working at your workstation.
4. Make simple exercises with your arms every once in a while so you don't get stuck in the same position. Make your hands turn in circles palm open until you hear horrible noises from your junctions :D
5. Force your employer to make sure that:
- light exposition comes from your left or right, not from above you. This reduces the need to make movements with the neck to read the monitor
- your chair has arm support
- you have a stand for your feet so they make a 100-120 angle compared to your legs
I took part of this from the italian law for safety of computer operators and i must say that it actually works. I'm working as developer since 2004 and i still don't have any back/neck relevant pain