Welcome to Koreanclass101.com!
Hope you are enjoying with us on Korean?
That is a really good question and here is what is good for you since you are starting right now.
It is absolutely the best to go by what Korean has as in sound rather than following what English has.
As you are well aware of, Korean and English are quite different and what it sounds is obviously different.
It is better if you go along with how ㄱ sounds like in Korean as in G or ㄷ as in D.
However, again we recommend you to go by what Korean has - it always helps better when you get to be on next step as if you are accustomed to memorize by what English has, later on you get to be confused..!:(
We do not want you to go through that confusion and hard time! So definitely better to also listen to what it says in Korean.
We would recommend you to take 'hana hana hangul' series as it also tells you how it sounds like!;)
Hope it gives you a bit of insight
Please feel free to ask us anytime!