Delilah Monroe wrote:
Best way to go about borrowing designer fashions?

Borrow? Delilah have you considered commissioning a designer to do a haute couture piece for for your session/narrative? I'm in your market and this has worked extremely well for me...  Oft a designer will give a healthy discount for the aforementioned usage... Additionally I've been highly successful at soliciting agency models by giving them the ensemble once it has been shot... The fashion industry is strictly business... trust me here... the sooner you lose the TF hobbyist mindset the more likely you'll rise in the industry... it's about selling clothes, not about making editorial statements... which btw, are fine for "creative testing"

Delilah Monroe wrote:
...I have no idea how to go about approaching a designer to borrow clothes. 
Where do I start?

Delilah one doesn't borrow from designers... they have a difficult time as it is competing against the off shore imports...

What to do?  First get a pull letter from the editor of the publication you're shooting for... then approach a wardrobe stylist with same... they will be the one to ensure your visual statement is achieve...  Fashion Designers have their own agenda and visual statements... only in major markets are you likely to find designers with the ability to pay a team...

Hope this helps

All the best on your journey...