I would recommend memorizing the vowels (모음) by heart.
아, 어, 오, 우, 으, 이, 야, 여, 요, 유... etc
As for the consonants (자음), you need to memorize at least the
그, 느, 드, 르, 므, 브, 스, 으... set, because 으 is the neutral tone.
Everything else can be derived, so to speak. You may wish to perfect them as you go along later.
Back when I first started, I would write them all down on a piece of paper and practice reading the entire set. Those are the bare minimums that I depended on initially.
You'll learn that when you speak, with the stresses and the flow and what not, Korean words are not always read the same way as they were written.
Keep this in mind, and I could never say this enough, Korean is Korean, not English.