When you're first learning Latin, memorizing the basic noun declensions and verb conjugations is a necessary step. By memorizing these parts of speech, you won't have to think twice when you see basic sentences and you can quickly move on to Latin's more complex sentence patterns. Memorization can seem boring, but if you repeat the declensions again and again, you can begin to appreciate the distinctive lilt and rhythm of Latin. Repeating the declensions for the word "this," can actually be fun: "Hic haec hoc, huius huius huius, huic huic huic, hung hanc hoc, hoc hac hoc." Practice writing them and chant them aloud whenever you have some extra time (in the car, doing the dishes). Soon they'll become second nature to you. When you're memorizing noun declensions and verb conjugations. it helps to have a common word to decline or conjugate. If you memorize the first three declensions (out of five), you'll be able to decline more than 60% of all Latin words. Concentrate on memorizing the nominative, genitive, dative, accusative and ablative forms, rather than memorizing the more rare noun forms.
Since Latin is not a spoken language, the significance of the language is found in reading words and texts. Latin sentences are like word puzzles, and you'll have to assess each one based on its verb endings, noun endings and word placement. Reading the poems of Catullus is one of the best ways to study Latin, since the poems are relatively short and simple, but still utilize a variety of literary techniques. Get versions of Latin texts that have both the Latin and English translations, so you can check for accuracy. There are also a number of popular books that have been translated into Latin, including Harry Potter, Winnie the Pooh and the Cat in the Hat. These might be fun reading alternatives to the dense Latin of Cicero and Virgil.
Wheelock's Latin is the bible for most learners of Latin. It provides a thorough overview of the language with exercises and an answer key in the back. Make sure you purchase the sixth edition or later, since the earlier editions feature some outmoded approaches to the language.
"Learn to Read Latin: Textbook and Workbook Set" by Andrew Keller offers one of the most comprehensive, rigorous methods for reading Latin, providing you with clear explanations.
If you need a lesson plan to stay disciplined, go to http://www.quasillum.com/study/latinstudy.php. This online mailing list group is set up for beginners to advanced learners of the language, who want a patient, yet organized and community-oriented way of learning Latin.