>>7293648I'm studying Classics at Oxford and this is what I've gathered from a few years of learning Latin:
The cambridge latin course is, IMO, the best resource for learning Latin (it has a great website that you can use in conjunction with the books too).
http://www.amazon.co.uk/Cambridge-Latin-Course-Book-Level/dp/0521635438Just make sure to learn the vocabulary lists at the end of every chapter or you'll quickly fall behind.
Once you've finished the cambridge latin course, buy "Kennedy's Revised Latin Primer" which contains all the grammar you'll ever realistically need to know and then just start reading original Latin and expanding your vocabulary whenever you don't know a word.
For looking up Latin words, Google "Perseus Latin Word Study Tool" which will tell you the meaning of literally any word you put into it as well as parsing the word for you (e.g. the case, number and gender etc.).
Beyond a certain point, you'll know all the grammar you need and then the only way to improve is to just sit and read original Latin while looking up words.
Good luck learning the best language there is.