Which Facebook ad objective should I choose, and should I use the Promote post button?

Votel recommends using only the Sales and Leads objectives. Facebook is very good at giving you exactly what you ask for, so a Traffic or likes objective brings you people who like to click and like things but do not buy or fill out forms. For most businesses every objective other than Sales and Leads is like lighting your money on fire, unless you are a large brand that only wants eyeballs.

Do not use the "Promote this post", "Promote your page" or "Promote your group" buttons inside Facebook. They put your post in front of people who like to like things, so you get likes but no sales. Go to Ads Manager at adsmanager.facebook.com and create a campaign there instead.

Facebook ads are structured as a campaign, which contains one or more ad sets, which contain one or more ads.

The offer you advertise also changes who Facebook finds. A no credit card trial tells Facebook to find people who choose not to pull out a card, so you may get tire kickers. A $1 trial, a $0 trial that requires a card, a low-priced challenge, a low-priced guide or ebook, or a booked demo tells Facebook to find people who will pull out a card or take a real action. Use the Sales objective for these paid offers. A free event with no money on the line is often not taken seriously, while even a small amount on the line makes people far more likely to show up.