1. Anything is better than nothing – Even if you can only spare five minutes for a quick vocabulary, it’s worthwhile to do it.  Language learning is a gradual, cumulative process.  Every little bit of exposure to the Spanish language adds a tiny bit to your knowledge.  Eventually, all these bits and pieces will come together to form an avalanche of knowledge.
2. You must study EVERY DAY- No exceptions, not even for holidays or special occasions.  As I said above, even five minutes of study time is better than nothing.  If you absolutely must skip a day for whatever reason, go back and repeat the previous day’s lesson again to make sure you’ve mastered the material before moving forward.
3. An hour per day is best- In general, you should shoot for an hour per day of good, uninterrupted study.  Some of you with busy schedules may have difficulty with this.  If that’s the case, shoot for 30 minutes or whatever you can manage.  The key is consistency.  For the average student, it will require between 250-300 hours of core Spanish study (not including conversation practice, watching Spanish tv, etc) to attain a reasonably-advanced competency with the language.  The more you study per day, the quicker you will progress.

For more on learning Spanish, check out my beginners Spanish, intermediate Spanish, and advanced Spanish study guides.