I love paintings and have several stashed in the loft after moving from a relatively large house to a much smaller one. I haven't bought anything new for ages as I have neither the money or the space but I tend to go for subjects that interest me personally and not necessarily anything that I think may become valuable in the future. After all if you are going to hang a painting on your wall you want to enjoy looking at it don't you?
I wanted to buy a sketch by Helen Bradley when my ex was at Salford University, but he said we couldn't afford it [it wasn't all that expensive] . Not sure how much her work is worth now. And a small oil painting of a Derby winner that was at our local antique shop; I certainly could've afforded that one but decided against it [at least it was post George Stubbs era!]. A friend of mine does very well by buying job lots of toys and finding things that are worth a lot of money [usually old dolls; some collectors of them are quite obsessive].