Captain Badass wrote...
I guess you could try focusing on something really far away and then on something close again to exercise them.
This is good for exercising your eyes. As for other methods, I suggest that you first cup your eyes with your palm to block off all light (make sure you don't put pressure on your eyes), and close your eyes until there is no more lingering traces of color/light left. Basically, get your eyes to relax first.
After this, keep your eyes closed and do the following movements:
-Rotate your eyes clockwise, then counter clock-wise.
-Make linear movements with your eyes. (i.e. Up to down, left to right, top-left to bottom-right etc.)
-Move your eyes around rapidly while 'focusing' on a single imaginary point that is darting around. The faster you do this the better.
These imitate eye movement in REM sleep and helps to reduce eye strain and fatigue. Of course you should repeat each of these a few times every session.
In addition to Captain Badass's suggestion, other methods to help improve your eyes is tracing. Hold an object at arms distance and move it slowly from right to left while following it your eyes moving, and keeping it in focus. (Preferabbly use something that stands out from everything else you see, like a yellow pencil.)