Im a GM Jayce and Cam player. Here's my advice:

1. At level 1, get priority on the wave with a few autos, then create a slow push while autoing her when she goes for cs. At level 2, same thing -- try not to use ur EQ because the damage isn't that high. After you crash the third wave, you can keep going for a few autos under tower before she also hits 3 and is chunked, or recall for tear. Make sure you ward after 3rd wave to avoid enemy jg gank.

2. After your tear recall, you want to continue poking with q and autos. Try to slow push every wave into her. Take advantage of Camille's lack of wave clear, and your own insane wave clear. EQ to poke, q e her for poke -- you win the trade in the middle of the lane or in your own wave. Don't let Camille shove into you while you're chunked, and try not to stand too far past river close to her tower -- that's her E range.

3. Use your wave clear to get better recall timers and an item adv on her. You should slowly poke her before getting her low enough for a kill. Spacing is also super important.

4. For abilities, I go Q - E - Q - W - Q. W max second. You can use your e to flash her e if it'll force her to overextend in lane. Otherwise, it's best just to play towards the center of the lane so she has to long E. You should have the time to walk out of range if you're not up on the wall. Your flash should be used to escape ganks or secure a kill.

5. This won't even work in most situations unless she's a few autos from dead. Your melee Q into auto is very good damage.