Step 1: Commit
To do this, you must commit part of each day to learn Latin. If you are a slow learner, commit 1-2 hours to this and ask someone to help you.
Step 2: Source
Find a database you can learn from. I used a first year Latin college textbook my mom gave me. If you can't find a book, you can use the computer, iPhone, iPad, iPod, etc.
Step 3: Notes
Take notes on what you have learned. Study them throughout the day.
Step 4: Learn Vocab
Write down and make flashcards over the vocabulary you have learned or have to do with your lesson. Quiz yourself often.
Step 5: Quiz
Have someone quiz you at the end of each week. Add on to the quizzes each week so it covers everything you have learned. At the end of the month have a quiz over everything. If you fail, consider doing another month or two. If you still can't learn try a different language. If you still want to learn Latin, learn the basics of either Italian, French, Spanish, or Portuguese first.
Step 6: Some Advice
As you might've seen already, a commenter Phil B gave the advice of using bibles. Go back and forth from each bible until the words start to make sense. You can also try decoding the words by yourself then seeing how much you got right by looking in the English bible. If you don't want to spend money on buying a Latin Bible you can use the Latin Vulgate Bible online.