There have never been more ways to learn French, and the technology and techniques have never been so varied and different.  If you had set out to learn French 20 years ago your options would be limited, but now your options are almost unlimited.  Nevertheless, not all methods are best.

Total Immersion - The Most Effective Method

To start with, the very best way to learn French is complete and total immersion.  This is hands down the most effective method.  It involves moving to France or some other French-speaking country and letting the people be your teachers and the culture be your classroom.  All other methods involve mustering some level of self-discipline, this method needs no mustering of willpower, you simply have no choice but to learn everything from the most basic ordering of food or drinks to the more advanced participation in a colloquial discussion of sports, say, or politics.  This sounds hard but it's really not, because you're getting a first class education with the best teachers - native speakers in their natural setting.  Most importantly, you're also getting a constant never-ending repetition of lessons, and practice, practice, practice.  It's the constant practice which, in any course, makes the all the difference.  You need to use the language to learn it, immersion lets you live the language as well.

French Courseware

Software is the second most effective method for learning French, for many reasons. 

First, it's cost effective.  The average cost for a travel package is in the thousands of dollars.  College or diploma courses are $500-$1000 per course.  Private instruction tends to be in the $25-$50 per hour range.  Software, on the other hand, ranges from $60 to $500, usually a one time fee, and the product lasts.

Secondly, language software has advanced considerably.  It is no longer merely a passive learning experience, you can now interact with the software, in some cases even replicating language immersion.  Also, modern language software often has speech recognition, allowing you to train yourself to speak French and letting you know when you mispronounce a word or use incorrect grammar, syntax or verb conjugations.  This is often as effective as having a personal tutor.

Thirdly, courseware makes learning French FUN.  These are not rote learning programs where you memorize long lists of words and phrases, these are games, puzzles, activities, exercises, compelling stories, gripping mysteries, riveting newscasts.  Some products even let you move around in an artificial environment, interacting with objects and people.  One thing is for sure, with courseware you will not be bored.

Finally, there is the obvious benefit of the course being self-paced, making an effective use of your time.  If you're a busy individual then this allows you to fit a course into your schedule.

Books And Audio CD's/DVD's

It used to be that you'd go to the library and pull out a book, then start learning a language.  You would see written pronunciation guides such as "Trois (tr-wahz)."  Generations of people learned languages using this method.  Nowadays the books are supplemented with audio CD's or DVD's which you'd listen to during your morning commute.    While there's nothing wrong with this, and it might just be what you need, it should be emphasized that this is a passive way of learning, there's no way to get feedback as to how well you're doing.