Hi Loesie,
I think the advice above is useful. I'd add a few things:
1) At 19, I would expect you to need an adult course (if any). All the secondary titles above are for 14-16 or so. Beyond this age, publishers consider students 'adults'.
2) Of the adult courses, I can't help you with a view on New Headway but both New English File and face2face are good courses. The New English Cambridge Course is a little old now so much of the content feels dated.
But ... the trouble is that these are classroom courses and as such, much of the material is designed for use in the classroom. While courses like face2face have very nice Workbooks, CD-ROMs etc. the syllabus is still built around that of the main book. Similarly something that began at elementary level would probably be very low for you.
So my advice partially echoes that above.
1) Get yourself some good grammar AND vocabulary books. The English Vocabulary in Use books (Cambridge) are good. Choose the one(s) that you think most suit your level. Similarly for Grammar. Flick through the many books out there and see what you think offers the right balance of explanation/practice. I would NOT necessarily advise an advanced book, though. They can be both difficult in terms of practice and sparse on information. And it sounds like you want some more guidance.
2) Read, read, read. Like novels? Get some high level readers - Cambridge, Oxford, and Longman all have series. Like film adaptations? Go for Longman/Penguin. Prefer original stories? Go for Cambridge.
You are not just improving your reading skills here, you are improving vocabulary, awareness of grammar, structure and everything else. After all, what does an editor spend much of his/her time doing? Reading. Similarly, writers (although you are not specific about what you want to write) MUST read widely for so many reasons.
3) Get other forms on input - TV, films, whatever you enjoy. You must hear language too - it will open up a whole new world for you. Look at the BBC alone - there are thousands of radio shows/documentaries in English - good listening skills are essential.
For your overall goal, accuracy may be necessary in the long term but a range of language skills is also important. Good luck!
Best,
Martin