Before starting to learn Finnish, I recommend these two steps:
- Learn a bit of grammar. This site is designed to do that, but it does not take a very rigorous approach and is mainly to get you interested and to know what to look for. If you have enough time and like a highly logical way of learning, I recommend the book Finnish: an essential grammar. It is not short, but the beginning is easy to read. I recommend you start reading it until you get bored, and resume when you have time or need more details once you are in the course.
- Learn some vocabulary. Starting a Finnish course is much easier if you already know basic vocabulary. I recommend you get some app that teaches vocabulary and use it in downtime. A lot of people use the app Memrise, and there are lots of lists of Finnish words on there. You can start with the most popular lists there, but beware: as you have learned on this site, there are many different forms to Finnish words, and the app doesn't capture all of the different subtleties of them. Still, it is an essential tool.
If you can do the two things above, your first Finnish course will be much more enjoyable.
- Wiktionary is the open source dictionary (companion of Wikipedia). The English site has definitions from all languages in English. It is a remarkably good reference on many Finnish words, and includes conjugation tables for all words and conjugation tables for verbs. When using any dictionary, remember that you may need to put some thought into splitting a word into it's parts or removing endings (though wiktionary search is good at finding all forms anyway).
- Finnish: An Essential Grammar, by Fred Karlsson. This is a reference book, not a text book, but has very good explanations for self-study. The first chapters are easy to read with no prior knowledge, and lay the same groundwork as in this site (though more formally).
- Finnish for busy people: Online grammar reference.