There is a systematic way to deal with that kind of a problem.
First: Define a coordinate system. Choose a convenient x-axis and y-axis, such that you'd have to take the minmum number of components. And the ones that you take, can be easily found out using some trig.
Second: The component method works because, components are scalars, they can be added and subtracted like any other number. So write down the x and y components of the velocities of the bodies before (say a collision) and after. Use the conservation laws for conserving the momentum in the x-axis and the y axis. (Never mix them up!)
Now, when you get the final components that you need, say a final velocity, or angle etc. Just change the components back to the vector form.