Graphing differential equations in general

I am having trouble recalling how to graph things. In class, we are learning about autonomous equations and population dynamics, and a big part of this portion of the class is about graphing the equation, finding critical values, and drawing phase lines. My problem is, I've been away from math for so long, I've forgotten how to graph things by looking at the equations!

In particular, I am having problems graphing:

dy/dt = ay +by^2, a>0, b>0, -infinite< y-knot < infinite

and

dy/dt = y(y-1)(y-2), y-knot >= 0

Please, please, please link me to any resources that have a decent tutorial about how to graph things. Much appreciated!!!