Dam right 2BB is fantastic as well as loaded brush (two colours) base colour and a small dot of the colour you're transitioning to, as you move your brush across the mini you go from new to base colour.
I Know what you mean about the white can be a bit chalky sometimes maybe a little mroe water or not play with it so long. I find cleaning your brush every few mins to get rid of the pigments that are hardening works quite well. I have a citadell skull white and army painters warpaint matt white, I do find the skull white harder to use for glazing (its the oposite to what it's designed for).
This is my way, not the best way but it works for me
I use vallejo glaze medium, as time goes on I use less and less and now mostly water, but its benifical to use the medium to get the hang of it, I swore buy it a year ago. Its hard to give exact ratios, you want it about 50/50 water-milk fluidity, I use it in all sorts of ratio's but this is about what I start with then dilute more and overlap other colour highlight on top to get the transition (just like your awesome face job!). Here is a pic I just did showing the dilution of paint, the last one I would call coloured water (Double the water v paint of previous mix), thats for softening the edges. The blob of white and dots and yellow thats older paint.
I don't wipe on a towel for white just on my thumb to check ( I do if I load the brush too much) faster it dries the chalkier it gets. You want it so the paint flows nice but not too fast off the brush or it gets sloppy. I did afew lines to show what thickness you can get, and on the nail trying to showing consistency. you can see the first 2 are qutie strong but not totally white reletive to the blob of white there. the last one you can hardly see.
I have a no1 pure red sable and a Kolinsky 1 anything like that the artist ones, not the short ones. If its got a good tip you dont need to go smaller.
Im sure you are familiar with this section but Im on a roll and thinking and writing as I go.
You can cut in the edges to make the white thinner too, if you want a super small line its easier just to go either side with the colour underneath, or reduce the highlight buy going back over it the other way, pulling brush towards the middle tone with a more diluted middle highlight colour.
Every ones different and like you say practice is key! hell if we were all the same we would not appreciate everyones diverse skillset.
Most of this SM is just white edge highlight but not all over it just in parts to help show the seperation and shine of armor, I did use the green to soften it. I also went back over the edges and one end with the diluted green to soften the transition and harmonise. I left one end crisp to show the shine. you can take back the white buy glazing other colours over the top.
Hope this helps
Happy painting
