As someone who tried mining Litecoin using a GPU just like you are planning to do, I would like to state that it is not worth it. Most people are using ASICs which can beat out any Graphics Card.
I ended up switching to mining Ethereum and Cryptonote currencies (mostly Monero) because that was more profitable without an ASIC.

So, my advice for you would be to either get an ASIC or switch to other currencies because LTC is not worth the effort with a graphics card.