Concealer erases your face so you can draw it back on. That sounds drastic especially to those who only use a bit of makeup, but it's true. Even good foundation works as a concealer, evening out skin tone, both in colour and texture.
Skin match might work, but some concealers are designed for certain conditions. Go lighter for undereye corrections, and go for a true match for pimple concealing. Try samples. If it covers up your wrist veins, that's your concealer.