Hello,
I would first make sure that you have good Comparables to help you figure out what the house is really worth. I would also make sure you get good Comparables to help you figure out how much you can really rent it out for. If your cousin is experienced he should be able to help you but you should also learn how To do it.
I would also work on getting pre approved and figure out what your budget is. Most importantly before I purchase the property I would pay for a home inspection report to make sure I am not missing any major issues.
Make sure your math makes sense, there are many resources here in BP to help you figure out how much should be accounted for things like vacancy, repairs, etc. make sure you read it and study it.
Once you've worked on a deal before you out any money down I would share the details with the BP community and ask for suggestions. People here are very well versed and will give you some perspective as well. Ultimately the final decision is yours, however it is very important to be as educated as possible. It's great that you have your cousin to help you, but make sure you take control of your decision because ultimately you are the one that will have to deal with any issues.
Best of luck and feel free to reach out with any questions.