I would use a grey concrete backdrop so that the colours pop off the neutral background. Also try and get some deflctors (or use those foil windscreen visors) and do the shoot around lunch time to the shadows are small.

Unless of course you want to move everything into the studio with an infinity wall and few sets of blondies or redheads (these are lights). Also maybe use a lightmeter as these make for perfect manual exposures and meter off a few different places.

Also shoot everything with a 70-200 if you have one. The model will look skinnier and it will compress the perspective better. Wide angles tend not to as so good for portraits.