If you don't want to or cannot study French with a tutor, in a class or in immersion, you'll be going it alone. This is known as self-study.
There are ways to make self-study effective, but it's essential that you pick the right self-study method for you. After all, you want to spend your time doing something that actually works.
So spend some time analyzing what's out there, and don't just take the first self-study path that comes to your attention.
Audio Training Is Essential
If you want to communicate in French (and not only pass exams or read in French), learning with audio is a must. There's a huge difference between book French and spoken French, and traditional methods will not prepare you for the way French people actually speak today.
French Language Books
French-language books such as children's books, bilingual books, and audiobooks are a great and relatively inexpensive way to improve your French, in conjunction with audio courses.
With Amazon delivering to your doorstep, it's easy to order French-language books these days. Hard-copy paper books are still the best way to train on a specific point of grammar and to do exercises. For all the rest, you'll need audio.
Reading "Le Petit Prince" is, for more advanced students, a wonderful way to expand your vocabulary.
It is a myth that all French-language children's books are easy. They are not. Children books are easier than most French books written for the French because they use short sentences, but the language is some French children's books can be quite difficult. Consider the language used in the Dr. Seuss books. They definitely would not be an easy read for a beginner in English.
Most bilingual-book series are taken from free-copyright books and translated into English. They were not typically books written for students. So they are still very difficult and will often feature older French vocabulary and expressions: Find out when your book was written, and take this into account when learning the vocabulary.
French Audiobooks and Audio Magazines
Both of these are a fantastic resource, even though most have been created for the French student. Much of what has been developed for the French is going to be difficult for a beginning or intermediate student of French, so difficult that they could be overwhelming and discouraging.
There are, however, audio magazines that can be used to good effect by beginning and intermediate students of French. Among the better audio magazines are Think French, Bien Dire, and Fluent French Audio (although the latter is probably better suited to high-intermediate students). There are also level-adapted French audiobooks and audio novels with English translations, such as the "À Moi Paris" series and "Une Semaine à Paris."
French Audio Courses
French audio courses are the ideal tool for the self-learner. A good audio course should teach you vocabulary and grammar, if possible in context, and, of course, pronunciation. It should be fun to use, direct you through a well-proven learning path and nurture your self-confidence.
Because they involve a lot of work, these courses are usually quite expensive, so look for a "100 percent money-back guarantee" disclaimer, a trial period or extensive samples.
Among the good French audio courses: Michel Thomas, Assimil, and French Today.
Rosetta Stone language books are a great, fun tool to develop your vocabulary, but they are very light on grammar. This may be fine for other languages, but it is a true problem for French.
Do Your Research and Find What's Best for You
There are, of course, still more methods to learn French. Do your research and find out what methods best fit your needs, goals, time and budget. You won't be sorry.