Ok you asked for a critique - this is only my second time doing this so I'll do my best ^^.

First of all well done for reaching outside of your comfort zone - it's the only way to learn new techniques and see your strengths and weaknesses.

Well done on the pose although if you really want to get it down pat try using references from stock images here on DA - one of the best is :iconsenshi-stock: but you can use the search feature to find what you're looking for as well - I find just browsing the stock can give me inspiration for a picture! That being said well done on the feet - they are tricky to get right ^^

So lets get down to detail. I know your just getting in to shading but once you've decided where you light source is then along with shading there has to be highlighting - so where does the light hit first on this picture it would be the top of rei's chest - her knees her forearm and a bit on the folded out parts of the fabric - what helps me is if I highlight it in a lighter colour (not quite white) and then use filter->gaussian blur - it's a bit of a cheat but it will help you in the beginning - same with the shading - don't be afraid to go to dark - I can barely see any shading on their skin - it will help give definition and remember - fabric reacts differently to light than skin and hair so play around with it and use real life examples as reference. Also remember what kind of light you're working with - here you've set the scene at night but you've lit them like it's day - if the light source was meant to be the moon behind then then there would be a lot more blue/purple shadows.

Now - lets talk about detail - in my experience it's the little things that can make a good drawing, great! I noticed that in a lot of your drawings you don't include eyebrows as a result you can only do so much with facial expressions - personally I've found the eyebrows play a huge part in being able to express emotions - especially when doing anime style drawings. One last detail I'd like you to try is with the hair - Hair in rl is made up of thousands of tiny strands - so instead of just outlining the shape of the hair and colouring/highlighting it flat - try drawing different strands following the shape of the head and flow of the hair to help give it more definition and depth.

You have posted a phenomenally large amout of deviations in the past five years - which is great and when you look back you can see how far you've come - try taking a bit more time now to add in the extra details and I think you'll see an even bigger growth in your talent!

I hope this was helpful and if you have any questions don't hesitate to ask!