1) I've seen people swear by the
GW one if nothing else is available. Try to get a local good quality 000 one. But before investing in one, try taking care of your current brushes and practice cleaning them and such. Check online tutorials for that stuff. Sure some of the brushes MIGHT be total crap but most people I've seen just have no idea how to care for them. I'm not saying you're one of them, just a friendly heads up if you say they're breaking up too soon.
2)I think washes are supposed to be the very last thing you apply to a model, unless you're doing incredible highlights.
I'm kind of a noob but just a few quick criticisms:
1) Something is VERY odd on that tone of white, I'm not sure what it is tough, must be the cleanliness in some parts of it or something. Maybe it's just me, I've been known to find some colours strange.
2) Those view slots on your rhino, paint the interior of them also gold or a darker colour.
3) Get some side views of that rhino
4) I'm also guilty of this, but drill those barrels as soon as you get a hobby drill.
5) Are those arms part of the scenery? Did you magnetize them and stick them nearby so we can look of them? Just checking... I've seen smart folks do strange things...