I've discovered the best way (at least for me) of looking at paintings. Imagine that a particular painting (modern or old) was on your bedroom wall throughout your childhood. Not a painting you chose or even liked particularly (although you might have done) but put there - for whatever chance reason - a painting which you lived with and looked at morning and night as you got up and went to bed - or sat in there reading, through your formative years. I find this process a relatively easy thing to imagine when - today - appreciating any painting. Even if one looks at it only for a minute or two, you can make it become that painting on your childhood bedroom wall and appreciate it in that light, as if you've lived with it. Try it.