I learned this principal about 25 years ago and it's still as valid today - AIDA - which is:
Attention
Interest
Desire
Action
It's used in direct response copywriting which is really what web copy is.
Basically, your copy has to grab their attention, make them interested, then make them want whatever it is your selling, and then take action - usually that's to click on the link and take their hand off their dick and take out a credit card
