B.O.B - muddiest point

My muddiest point in this whole unit was solving and finding the solutions for sine, cosine, tangent, cotangent, cosecant, and secant. I figured out how to do the short ones with one or two solutions but I had trouble with the harder ones. My problem is trying to find out how many solutions there actually were and which ones to use. I always seemed to use the wrong ones and had problems getting the right answers. I'm slowly but surely learning the steps to figuring out how many solutions there are and which ones to use.