I've been trying to meditate regularly - but have only been doing a very basic 'watching my breath' one. Just simply breathe in for 4 counts, out for 8, hold for 4, then start again. Actually very calming and it's supposed to be very beneficial health-wise as well (learnt it at yoga - will have to look up the reference my yoga teacher gave me).

I've never been able to 'see' colours, or anything else when I meditate. But when we used to do visualisation meditations at yoga, I would just repeat what the yoga teacher was saying to myself and try to get the feeling of it happening IYKWIM?