Your offer is the most important part of your campaign. If your offer is a dud, nothing else will make the campaign profitable in your funnel and it will all be a waste of time.
If you log in and explore an affiliate network, you will see thousands of offers from different verticals. But remember, not all offers are created equal.
Generally, the country that an advertiser permits traffic from is in brackets or clearly stated somewhere. Most offers will have different pay-outs. Do not just pick one that pays the most and run with it!