Welcome frankie! LOL this is a great start and while Ventress is definitely a tricky costume, it's not unattainable!
ladyb is our resident expert on this version of Ventress so hopefully she can give you some pointers. Nonetheless, I'll add my 2 cents
Your buckle definitely needs to be bigger. When I was making my Sash-belt buckle I needed to figure out a good size proportionate to me, so I cut discs out of paper, held them up to my waist in the mirror and compared that to the reference pics. I had to do this a few times until I found a size that looked right.
For the shirt, are the stripes you have now removable? As per the CRL, the stripes are optional (states "may have"), or I would do like ladyb and keep them as small pin stripes.
For the collar, the best results I've seen are when the collar is sewn directly to the shirt - do-able if the collar is made of pleather/leatherette fabric, but can be problematic if the collar is made of real leather when it comes to giving it a wash. Personally, I find your collar a bit long and would suggest taking some of the length out of it if possible. It also appears to be missing the horizontal lines (seams) along the chest/shoulders/back sections, which will need to be added.
For the makeup, here's a good read on doing the baldcap
http://theflagshipeclipse.com/forum/vie ... =70&t=1068
How you apply the makeup will depend on what kind of makeup you're using. If you're using liquid makeup (water or alcohol-based) I would recommend applying it with an airbrush - light, even coats is key.
And patience! Lots of patience Good makeup takes time. A good baldcap and makeup application takes upwards of 4 hours in my experience.
Good luck and looking forward to more pics