Consistent quality uploads. The unlimited upload flag is as much a user promotion to a trusted position as it is freeing up manpower requirements from the moderation queue. If you're uploading daily, try to go a week with all posts approved. Study what makes it and what doesn't, and make your weeklong success quality the baseline. Most importantly, upload not because you're seeking a promotion, rather because you found something good that you want to share.
picnic Thank you for informative comments. is there any special requirements to be unrestricted uploads?
Having a very... very low deletion ratio certainly helps, when I'm the one handling that one out. That's kind of the point. If one ends up with almost every single post of theirs approved, then they might as well bypass it for me. I do try to weigh the recent performance over the beginning one, when one might have been much more prone to mistakes though. It's still a steep step to make.