Looking at your best scored image what I see:
- you can be more brave with the highlighting
- work more on the transitions, the black-grey is a bit rough at some parts. (+ even though you have transitions, but for SM-s it's easy to fall back to edge-highlighting only like GW, so please remember, that even SM's need a color transition between dark and light besides the edging)
- well I have to agree with Zab, for 8+ you'd need more elaborate bases. Think them as helping tell a story (and for units a unitbase could be helpful too, so you can make a bigger scenery that integrates with the figure's bases)
- well it's not really an useful advice for iron-hands, but learn color-theory and learn to use colors more effectively.
- shading with multiple colors on the metals help too (so not just a wash, but a controlled shading with blues-greens-browns and black for example, the color is mainly to add interest or make something pop against the others (see color theory above))
- it will be a b*tch to photo, but learn to use textures, at least gloss-satin-matt. For example (staying with IH): a metal part shaded with brown and glossed to make it look like it's oily besides a black armor part, that's given a blue-ish shade + matt varnish --> double, even triple contrast (dark-light, warm-cold, glossy-matt) (Btw the one above may not work, but it is an idea to try)
