Copywriting (and PR) are only for hacks who can't cut it as 'real' writers. Yeah, keep telling yourself that as you wait tables and finish your novel. Working in advertising can be a lot of fun and keep your mind if constant brainstorming mode.
Copywriter John Scott Lewinski has some tips for those breaking into the field:
1) The purpose of all sales copywriting is to sell. Not to inform. Not to educate. Not to persuade. It is to sell. Every sentence and every word should be devoted to selling the product or service indicated.
2) The same principles that apply to other forms of writing (prose, non-fiction, novels, etc.) apply to copywriting. Your work should be functional, precise and elegant in usage. Edit youtself.
3) Your audience is your buyer. Service that audience. Present him or her with the information they need to purchase your good or service. You are doing them a favor by fulfilling their consumer needs.
4) Believe in the product or service you're selling. If you can't do that, walk away from the assignment.
5) Your audience is not stupid. Do not try to dupe them. Be direct and honest with them -- while always believing you have news on something they want.
Want to learn more? Take John's Intro to Copywriting course later this month!