Duplicate Rewards for Computer Hacking
You can duplicate the rewards (XP, credits, and stop/nuke items) that you get for hacking a computer. To do this you need to save before hacking a computer and while you are on the 'access granted' screen reload your save (do not press the 'ok' button) and hack it again. This can be repeated as many times as you want per computer but failing or aborting a hack will reset the stacked up bonuses.
Upgrade your Hacking and Strength whenever possible until you can pick up turrets as they contain unlimited ammunition. The turrets can then either be set down or you can allow them to fire while you move. This can also be done with robots.