The obvious way is to learn korean. So what if you do not know enough korean yet? Do what I do.
For example, I had to pick up corn oil. What I did not know was what which one is of good quality. So I did what any camper in Q3 does – camp @ the place where there was as ton of corn oil. Ultimately I found a grandma who picked up a bottle of corn oil. Well I just followed her. Eventually I bought a lot of stuff just following her. I followed a lady who had kids to pick up moisturiser. I followed kids to pick up good chocolates.
Barbaric, but effective.