The uniform acceleration equations
Choose the equation that holds the three quantities you know plus the one you want, and keep the signs consistent.
A worked example
Starting from rest at 2.0 m/s squared for 6.0 s: v = 2.0 x 6.0 = 12 m/s, and d = 0.5 x 2.0 x 6.0 squared = 36 m.
The mistake people actually make
Do not use d = vt with the final speed while the object was still accelerating, as that overstates the distance. In projectile motion the horizontal speed changes where it lands, not when.