I usually telescope a bill by carefully rounding the outer edges of each side the bill slowly and rolling each edge toward each other until I obtain the desired curvature. You want to make sure you use a rounding motion as you do not want to form a crease in the bill. The baseball/rubber band trick works too, but I prefer my method mainly b/c it gives my nervous ADHD self something to do while wearing a hat all day...
As far as what is "in", the trend today is to keep certain types of hats bills flat, like the New Era 5950's and Pro-Line hats our team wears (hats with larger structured crowns). This is not the case with unstructured hats as the bills usually come from he manufacturer telescoped slightly and it is still considered "in" to telescope those types of hats.
I telescope all my bills and do not get into the whole trend thing. But, to each his/her own....
The trend today also is to keep the crown high, but I usually break mine down ASAP. Two methods exist that I know of. One, as mentioned previously, is sticking your head in the shower with hat on and then using your hands to form the crown around you head. The other I learned from baseball players. You boil a big pot of clean (or dirty if you like that look) water and then carefully place each corner of the crown in the boiling water and it pretty much breaks the crown down right there. Let it cool after a few seconds then place it on the head and use your hands to form the softened crown around your head. The boiling method pretty much insures that the break in lasts…Also, if the hat is too big, placing the back end of the hat in boiling water for a few seconds then wearing it after it cools for a second will shrink most wools and cottons. Be careful though. If you leave a wool hat in too long in boiling water it could shrink too small. Be conservative with how long you leave it in the water, and be sure to wear until it is fully dry as the hat will shrink to the size the object it surrounds. If you take it off too early, it could shrink too small. So do this method on a day that you intend to wear a wet hat a good portion of the day...