NicholasBaker2017 I think CAT tools are overrated. Yes, we need them and it's great to have them, but lately it seems like the translation industry is all about tools and not translations.
So from this point of view, I think that the best think to invest in, are good writing and translation skills. No amount of tools will make up for lousy texts.
This being said, you will need to work with CAT tools. But don't rush to pick one. Start with getting clients first. Slowly, you will find your way around and you will also discover the best tools for yourself.
I work with memoQ because I have a team of 40+ freelance translators. SmartCat seems to be a good option for individual translators working with more clients. Trados is expensive, but there are many translation agencies and companies out there using it... so it might be an advantage knowing at least how the tool works.
If you want to try some subtitling tools, I recommend doing some voluntary work for the KhanAcademy or Coursera... You do something good and you learn a great skill. ?
These were my 2 cents... I hope it helps. ?