That second portrait is wonderful due to the amount of detail given to the shading. The contrast is on the right track. Compared to the other drawings it looks as if a lot more time and care went into it. I agree with Topcross about the highlights/shadows on the still life cup.
I'd suggest practicing gesture work (try to get a flow going, become more organic with your hand, head over to posemaniacs and do some 60-90 second gestures). Also, practice more varied range of line weights, try making a drawing with 6-8 different line weights. You could also build on the cup-still life with different line weights to make it pop more. Keep up the good work.
Ok so heres still life number 3, really not happy with this one but each one is practice again, but I'm wanting the next one to be a bit of a step up from these hopefully. Oh and I;mthinking the midtone value on this is way to bright, not sure though.
here is still life number 4, not even gonna comment about how this one came out, except the fact that it had a lot of hard edges which was proving really difficult to render out, so if anyone has any advice on that would be much appreciated .
So yay, out of my still life studies I'm kinda half happy with this one so far, at least that I think it's better than the other ones so far. By the way that thing underneath it is a really badly rendered puddle thing lol.
I would have to agree with Voodoo_Mama, working on the fundamentals would be most beneficial for you at this stage, you are jumping all over the place trying different things.
Most evident seems to be lack of understanding of saturation. Simply put, saturation is the intensity of colour, it varies massively, just like hue, so take your time to figure out what goes where on the photoshop colour picker and do some more pieces from life. Really try to take note of the colour, value and saturation you are seeing
Ok, so heres still life 7, was focusing only on the colours not the overall picture. Definitely going to just do greyscale for now and focus solely on the values and form. So ye if anyone can shine some light on any of this would be much appreciated.
Ok, so heres some new posts with more than just the annoying still life studies lol. Theres two studies and two sketches I did of my insanely untidy room. The first was just a quick one and the second was more of a finishedish one (might colour it in photoshop sometime).