Don't focus on writing less code... focus on the code you end up with being more readable.
Sometimes an if
statement will be more readable. Sometimes the conditional operator will be more readable. I like the conditional operator in cases where it makes sense, in terms of different ways of calculating one logical value (e.g. a discount, based on the age of a customer). I don't like using it in convoluted ways though - there's nothing wrong with using a full if/else where it makes sense.
It's worth remembering the null-coalescing operator too... so instead of:
string shipTo = customer.ShippingAddress != null
? customer.ShippingAddress : customer.BillingAddress;
you can use
string shipTo = customer.ShippingAddress ?? customer.BillingAddress;
Again, it's only useful in certain situations - but in those cases it's really handy.