I just put a clear bra on my 3 yesterday -- following up to Msugi07's great advice, the one lesson I learned is that you MUST get the soapy water washed out from under the clear bra as you adhere it to your car. I ordered mine from invisiblemask.com and they have excellent instructions on their website and included with the shipment. I only did my hood and front fender edges, not the whole lower bumper, because that looks too complicated!
Their instructions have you use a soap and water solution to position the clear bra, then squeege the center of the bra just enough to make it stick in place. Then they have you lift one side and use an alcohol and water solution to rinse the soap out from underneath, then repeat for the other side. They suggest spraying the alcohol soultion, but I found that literally pouring it over the car and underside of the clear bra works much much better. I did 2 cars this weekend, the first one a black Acura TSX, and it looked horrible because soap was trapped under the surface (not air bubbles, just white soap residue). I then did my car, pouring the alcohol mix rather than spraying it, and it came out great! invisiblemask.com also gives you a great little silicone squeegee which is soft enough to not tear the clear bra - don't use a hard plastic squeegee! If you take your time and use plenty of the water/alcohol solution, you have enough working time to smooth it out nice and you won't have any air bubbles.
And yeah, i ripped the clear bra off the Acura and there was no damage to the paint, just damage to my wallet for wasting $130!!!
Oh, and this is DEFINTELY a two person job.
The trickiest part was the area around the grille, on each side, where the hood dips down to surround the grille. You actually may need to stretch the plastic (just a little bit!) to get around this area. I didn't stretch it quite enough, but I was able to trim the excess with an exacto knife. Also, the ridge line on each side of the hood (which leads to the grille) is a bit tricky since the clear bra doesn't really stick to the car until you squeegee the water out from under it. Keep at it and you'll be able to get over these ridges. Oh, and I used bug and tar remover to clean the area first, because that will remove wax but leave the clearcoat. The surface must be perfectly clean for the clear bra to stick. I hope this helps!!!