It depends on your goals. If all you want to do is become a break-even player or a small winner at the lowest stakes, you can accomplish that without any tools other than reading forum posts. That said, your rate of improvement won't be nearly as rapid as it could be. That's fine if it's not important enough to you.
I'd suggest at least checking your local library to see if it has any decent books, plus there are free videos around as well as free trials of some training sites.