This is correct for a mid-level developer.
Jr: $50-$80/hr
Sr: $90-$150/hr Jr: $50-$80/hr
Sr: $90-$150/hr1. Specialize & productize your output, then offer fixed pricing. Customer gets a predictable result for a predictable cost, you produce something you can estimate to good accuracy while earning a higher effective rate.
2. Retarget your deliverables on business value instead of a technical spec sheet, then charge accordingly.
Note that both of these involve business development strategies, not improved technical skills.
I know a couple people in the contracting business, and they all say that having their own app(s) in the App Store was the most valuable aspect for marketing.