This is a good video by badmephisto that goes over some tips and tricks for learning the OLLs and the PLLs. If I remember correctly from when I watched it, one thing he says is that to learn an algorithm, just repeat it for a certain amount of time until it is in your muscle memory.
Also, when solving, you will need to recognize which case you are dealing with so that you can use the appropriate algorithm. So, when learning one, make sure that the recognition of the case and the algorithm go together.