I have forever loved this outfit from J-Lo and now that paperbag trousers are taking over the shops, it is a great source of inspiration on how to wear them well -- especially if you have a curvy bum and thighs, like our amazing model. Because whilst these high-waisted trousers elongate the legs of those with slim thighs/not much bum to speak of [yes, highly recommended to ladies with longer torsos/shorter legs], they can be a minefield for curvier ladies, over-emphasising their hip area, from both back and front.
So let's have a close look at how Jennifer makes them work:

Jennifer has chosen a pair of trousers in a neutral grey colour and a classic, relatively heavy tweed fabric. Both serve to camouflage: the colour blends in, the fabric holds its own shape and does not cling.
The cut of the trousers is figure skimming, neither tight nor loose, and cropped but relatively wide at the calf/ankle.
The waist is emphasised with a look-here black belt, drawing the eyes upwards: a great way to elongate legs.
The choice of top is key: first, it is a low-cut scoop neck, which shortens the torso and thus elongates the lower half of the body; plus it is roomy and not fitted, providing a bit of balance to the hips.
The cardigan is a great stroke too: it obviously hides the bum and widens the upper body, but also adds a nonchalant vibe, and its black horizontal stripes complement the belt perfectly, drawing further attention to the waist.
Finally, the booties. They are a controversial choice, not the most flattering pair ever, however -- they are heeled [further leg elongation] and low enough to show a teeny bit of skin at the ankle, which just about saves them.
Overall, the whole outfit is very well colour-schemed and designed to draw the eye to Jennifer's waist, which is also made to appear quite high. There is no indication that her hips or bottom are [famously] curvy, she looks streamlined and trim.
How to copy? The key advice is to make sure your trousers are of good quality fabric and have a similarly fluid cut. Then just follow the above steps: use a contrasting belt, a low-cut, fluid top, heels and a well chosen cardi or blazer and sweep in the compliments.