You could start by factoring it to

(x-4)(x-2) which gives two points

(4,0) and (2,0)

x=0 gives another

(0,8)

If you know the vertex equation

x=-b/2a from ax²+bx+c or half way between the two y=0 values gives

(3,-1)

After you plot those, they should let you pick any x values that will fill in doubtful domains.