If you already have keepering experience then so much the better, however the following will be a big help. It is surprising how often zoos will need a driver, it is often asked for in advertisements for keepers, particularly by smaller zoos. Again this is something many keepers have to learn to do. If you are already versed in the art in reversing a trailer you get yourself an extra point. Any attraction which is open to the public needs a first aider, someone accredited by the Red Cross or St Johns Ambulance in the First Aid at work course.
Zoos have to pay to train their own staff.
This costly in both time and money so if you have already got this potential employers will look more favourably upon you. Get yourself a firearm certificate. This will normally involve the use of fireams. If you already have a certificate this is another plus. Although larger zoos will have their own records officer the smaller zoos usually do not.