First of all, not having any teaching experience is not a problem - there are many many schools who recruit newly qualified teachers - everyone has to start somewhere, right?
Not having a university degree will prevent you from working legally in some countries due to requirements that foreign workers have a degree, but the majority of countries will still be open to you.
So, in summary, it definitely will not be a waste of time and money to take a TEFL qualification. The type of course could be important though. I would recommend taking a classroom based course of a minimum of 100 hours, which includes some observed teaching practice. The most recognised of these type of courses are the CELTA and Trinity Cert TESOL. These courses are usually studied over an intensive 4 week period.
There are some good quality online courses available, but you will find that they are accepted by fewer employers than something like the CELTA - generally speaking the shorter and less classroom based your course, the more limited your employment options will be.
There is of course the issue of cost, however - online courses are usually significantly cheaper than classroom based ones.
I would suggest researching some current jobs listed on this and other ESL job sites to get an idea of the typical requirements of employers in some of the countries where you might be interested in teaching, and take it from there.
I hope that helps - good luck!