Can't believe I'm even having to say this one but folks please check that your websites are smart phone compatible.
I've stumbled upon a few photographers of late who are still running Flash sites and way too many hijacking my computer screen with automatic pop up window enlargements.
I'm sure there's a technical name for when that happens but I'm too full of swears to learn it!
Just thought of another good point. If you think that the above doesn't include you, double check your mobile phone number is copyable or clickable from a phone too. Ta :)