A few designs for workable ads are needed. If the layout only works for one size; then other designs for other sizes are needed as well. Our biggest ad sizes are 300x250; 160x600; 728x90 - to a lesser extent, ads at 125x125x 190x140, and 468x80 are important.
The KEY element in every ad is an international phone number; this is a must.
A tagline to draw attention would be nice; provide your own ideas or leave space for me to be able to insert our own tags.
Final files would need to be in PSD format so I could change the phone numbers.
Our usual ad consists of a picture of a girl, and a basic messaging. Better text layout/font choices - background colors; better images of women/phone callers (I'd suggest women of an South Asian/Hispanic complexion) have worked for us - but if you've got something special up your sleeve; I'm more than welcome to try something different.
If you include an image of someone; please include the licensing cost/details of the image in your notes.
Bonus : Some future ads will be formatted for mobile phones; so an indication that the layout *could* be downsized for much smaller ad spaces would be great - but don't let it limit your creativity for the larger ads.