Original Lemon Still Life

Have I ever posted this one? It was my first still life and it's based on the same photo as the acrylic underpainting I posted a few days ago. I've often looked at it and wished I could do this differently and that differently, so now I get the chance (see earlier post). Unfortuantely, my first go with the oil over the acrylic underpainting didn't go well. I think it might be because I use cheap paints and my yellows just don't have any umph. As soon as I add any thinner or another pigment my yellow just vanishes. It may be time to buy some better paint.