First of all, it is imperative that you have good grades. So work on that. Mathematics is considered as appropriate background for an AI masters so having good grades will get you on the entry radar! Then, since you are on your last year you could select an elective related to AI or even better choose a final project on AI, if available on your course modules. Furthermore, you could check whether a professor in your department's faculty publishes with students and try to work with him for a while. Having published in the field would help your academic CV.
Apart from that, in order to gain experience you could check online courses but at the same time work on your own projects. Andrew Ng's specialization has helped me a lot, but what helped me even more was applying the taught concepts and creating a portfolio(e.g. create an API, try to implement papers etc). There is also a Tensorflow specialization among many other courses that you could check on the web. Forming a group would enable hands-on experience as you could collectively work with others and learn from them. So search for local AI groups and within your university, there should be someone you could work with.
Coding wise, as you probably know python is very popular in AI-ML but C++ and Java are viable options as well. Just decide on what suits you and focus your effort on a single coding language.
Another approach you could evaluate is applying for an AI internship if possible. Check your university's research lab or your companies in your area for a data-science or ML related position. This way you can learn and apply concepts while enhancing your CV. In general keep an open mind and do not try to focus on a single AI sub-domain early on. Chances are that you 'll change your mind!
Finally, check the prerequisites of the schools that your want to go to, thoroughly. Follow them and their alumni on linkedin to see what they are up to and try contacting one or two in order to ask questions. Getting inside information is key!
Good luck and may you accomplish your goals!