Ive noticed a trend around my area of either white bottoms (usually shorts) and plain black top or the other way round. I think these would look great with a plain black tee and black sandals. Maybe with a thin metal chain.
The matching top is fun, if you can find it. And then the whole outfit would look good with some bright jewellery?
A black waistcoat and heels might be fun if you were going to a party and wanted to add some drama.
Have fun dressing your new trews :)