Korean consonants were designed to look like the shape your mouth makes when saying them. ㅁ looks like a mouth from the side (lips closed = M). ㄴ looks like a tongue touching the roof of your mouth (= N). Once you see it, you can't unsee it.
The 14 basic consonants
ㄱg/k — 'g' at start, 'k' at end
ㄴn — always 'n'
ㄷd/t — 'd' at start, 't' at end
ㄹr/l — between 'r' and 'l' (tongue flap)
ㅁm — always 'm'
ㅂb/p — 'b' at start, 'p' at end
ㅅs — 's' (but 't' at end of syllable!)
ㅇsilent at start, 'ng' at end
ㅈj — as in 'jump'
ㅊch — as in 'church'
ㅋk — strong 'k' (with air puff)
ㅌt — strong 't' (with air puff)
ㅍp — strong 'p' (with air puff)
ㅎh — as in 'hello'
The 3-tier system: plain → strong → double
ㄱ → ㅋ → ㄲg → k (with air) → kk (tense, no air)
ㄷ → ㅌ → ㄸd → t (with air) → tt (tense)
ㅂ → ㅍ → ㅃb → p (with air) → pp (tense)
ㅅ → (none) → ㅆs → (none) → ss (tense)
ㅈ → ㅊ → ㅉj → ch (with air) → jj (tense)
Put your hand in front of your mouth: ㄱ (g) = little air. ㅋ (k) = big puff of air. ㄲ (kk) = NO air, throat tense. This is the trickiest part of Korean pronunciation but you don't need to perfect it right now.
ㅇ is the sneakiest letter. At the START of a syllable it's SILENT (just a placeholder). At the END it becomes 'ng'. So 아 = just 'a' (ㅇ is silent). But 앙 = 'ang' (ㅇ at the end = ng sound).
Quick Quiz