It's very match-up dependent because she has so many options(because of both her abilities and keystone options) and lacks a lot of up-front power before Trinity.
In a lane that many weak Camille players may consider very difficult to trade in like Garen your trading patterns need to be less about extended 1:1 fights and more about quick one-sided trades. Prep Conqueror on the wave, Q a minion to prep Q2, run up to him with your bonus movement speed and hit him with Q2 before he can cast his Q onto you, negate his with your shield and hit him with the true damage and then just back off with your movement speed all the while poking at him with W to prevent him from healing with his passive. Your all-in is literally inescapable so these sort of "death by a thousand cuts" playstyle works really well.
Against some champions with more waveclear than you like illaoi, you are just forced to brawl with them for lane control. Take PTA start Q and just start wailing on her if she fights you for lane control, it's a high skill match up and it almost entirely comes down to you being able to outplay her skillshots and fucking kill her. 90% of the time in an Illaoi lane either I or the Illaoi dies by level 4 because that is just the nature of the lane.
Against some lanes you have no agency without your jungler before you hit Trinity. There is nothing you can do to Akali, she gets to do whatever she wants and you cannot deny it. I start W and just farm as safely as I can and ask my jungler to come when she overextends.
Basically the point I am making is that it's very specific and different players even play match ups differently based on preference. But the most general advice I can give you is to start Q and take PTA into any match up you think you can fight 1v1 and just brawl with them in the early game and take comet in every other mu.