I have long loved ponchos. I even bought one while in San Diego in 2007. They are just an easy way to add a layer of warmth to your outfit while not wearing a jacket and look great with jeans and wedge sandals.
Above: Asymmetric cashmere poncho by Crumpet
Ponchos look good on the "long and lean" body type as well as other body types. The trick is getting one that fits in all the right places and does not look like you just threw a blanket over your shoulders.
You want it to look flow-y and not blanket-like. Asymmetric styles, I find, are the most flattering to a figure. Like the one above which I wish I had the money to buy!
There are cheaper versions but, sometimes, cheaper can be more "blanket" in appearance.
Above: Soft Side Poncho by Jules Allen
I love the colour-blocked pattern to the above poncho but it tends to lean toward the "blanket" in appearance. You walk a very thin line when looking at ponchos since many fall into that "blanket looking" area.
This is why it is important to try the poncho on before you purchase it and see how it fits you.
Does it allow for your figure to show through? Hug the right places? Give you a hint of breasts? Not appear as if you are wearing a very short Snuggie? Is it made out of comfortable material?
Above: Leila Poncho in Black by Bennet Malibu
All this is important and trying the poncho on will help you decide if it suits you.
You may also want to see if the pattern on the poncho (if there is any) suits you or overwhelms you. It should be eye-catching but not distract from you.
Above: Holly Poncho by Bennet Malibu
After all, you are wearing the poncho, the poncho is not wearing you. See if it flatters your skin tone and hair colour. This also requires a try on and glance in a mirror.
So embrace the poncho, find the one that best suits you figure, skin tone, and hair colour. Avoid the blanket look by trying the poncho on for size. A poncho can be fun to wear, so wear one.