And wondering how you should go about developing your clothing line in a way that ensure's your ownership protection?

We have to tell you we are not lawyers and this is not legal advice. We are just sharing business advice that has been helpful for us.
Copyright, Trademark, Or Patent, which is right for your clothing line?
There are different types of protections that exist for your intellectual property and clothing line. However, the most relevant is a Trademark to protection your brand and logo from being used by other people. Here is a quick summary;
- Copy Right - These are used to protect works of art. While your logo may be a "work of art," copyrights are more generally used for paintings, books, songs, etc.
- Trade Mark - This is used to protect your business name and logo. It gives you ownership over the name of your brand and logo, so that similar "look alike" business cannot operate in your space (apparel). Please note, that you will still need to enforce your copyright, which can be a tremendous amount of cost and time. But having your Trademark gives you the legal "high ground" should there be a conflict in the future. It will also discourage credible competitors.
- Patent - This protects your intellectual property, like an invention that you have created. If you are just designing shirts, hoodies, or hats, it likely doesn't apply. Again, you will need to pay to enforce your patent, should someone begin to use it.
Know that you know you need a Trade Mark, what's next?
Before you jump the gun and apply for your Trade Mark at the uspto and spend the couple hundred bucks, it's best that you research your idea to ensure someone else hasn't already Trade Marked it. If they have you will likely be denied and it's best to find a new name/logo.
You've done your research, what's next?
If you are confident no one is using your Brand name and logo yet, the best thing that you can do is begin to use it. Simply using your brand name provides you some Trademark protections. Additionally, you will be required to show photos of your Trade Mark being used when you apply. Finally, just using your Trademark provides you some basic level of protection.
Labels. Check. Now What?
Once you have your product begin selling it to make sure your clothing line is working. We recommend selling about $10,000 worth of merchandise before applying for Trade Mark.