Here's the thing, sure you may have had a couple inquiries and positive feedback on Facebook before launching, but chances are these were all from people you know personally who want to support you morally, but not really purchase anything from you.

Branding is your best friend, through your brand which in this case is "Die with Honour", you have to sell people a lifestyle not just a shirt. You need to figure out exactly who your target audience is, are you marketing it to skateboarders? creative types? rock musicians? bikers? etc.

From there start finding ways to build hype on social media. Do a photoshoot with "models" who fit the profile of your target audience, you dont need to spend a lot of money on this you can literally get friends to volunteer to model your shirts, grab a good camera, and head to the woods or a busy urban area or empty farmland and hold your own photoshoot. Create a blog site like tumblr for your brand where you can post these photos, or maybe even an instagram. Create a twitter account for your brand, hold giveaways every now and then, get your followers engaged in the brand.

Also make a Lookbook on youtube for your first line of shirts. This can be a simple video two minute video of friends modeling your shirts, with a little music in the background. This serves as a little promo for your line. Even if you dont have a good camera you can definitely film it on an iphone or good android phone camera and edit in whatever editing software you have on your computer:

Here's an example of an "urban" lookbook done which is very easily filmed: