uLearn.Photography - part of FilmPhotoAcademy.com
If you have any of these filters, then practice with them.   What do you need to do to achieve the strongest effect with a given filter?
If you don't have any of these filters then try these:
1) Stretch stockings or tights over the lens
2) Stretch cling film over the lens
3) With the cling film, make a hole in the middle of the lens
4) Use a coloured, see through sweet wrapper or similar over the lens
Find out what size filters your lens requires.  Have a look online and see how much different filters might cost.