This is like trying to hit a moving target....my reply copied from the first (or was it last) post
If you want that to be your primary subject go for it. If you can find one genre that stirs your enthusiasm it focuses the mind wonderfully. I would hold off buying that macro lens for a while yet. I don't know what the preferred focal ranges are for this kind of work but I am guessing a 100mm macro lens will restrict you.
Don't stop with the natural stuff though the last few shots you have posted have been a pleasure and the is very tangible improvement in evidence. I have a definite preference for shooting still life but as you have noticed I try to keep my hand in with other genres. Although this sometimes frustrated me I feel I need to do other stuff to learn the whole range of techniques that could be applicable to the still life.
The pics; First two need some fill lighting. Natural light is often best for this sort of stuff but you need to watch how that light source compliments your scene. Unless the light source is complimentary try to keep it out of frame. I think you realised this with the crop. But, this accentuates the unlit areas of the scene. I know you do not have photoshop but it may be worth giving GIMP a try. You can take several images of the same scene and light each shot from a different aspect. You can them put them together as layers and play with the opacity of each layer until you get the balance of light you require. You can of course achieve this by lighting the scene with several lamps and one exposure but unless you have the correct lighting rigs you will struggle.
Now the pumpkiny things. I have noticed that you often add objects to your set. I do the exact opposite and take as much away as possible. Cluttered scenes rarely provide the impact needed for still life. There are exceptions and some photographers successfully portray bodegón with quite complex compositions but these rely on the skilled use lighting.
Keep 'em coming