Promoting CPA offers by an email list?

Avoid being too salesy and looking spammy. That's it.

*Get email servers setup that have excellent delivery or sign up for an esp
*Join some cpa networks, or source your own offers to run directly with advertisers.
*Source (Buy, generate) data and leads in the niche you want to promote CPA offers too.
*Hire a copyrighter to give you better creatives then the stock ones the networks give you.
*Ensure your data is all clean and bounce free
*Run a slow warm up schedule on your new servers, and begin building some trust at this low volume with the top level domains
*Constantly review your stats and logs, and continue to do a/b split testing until you have found positive ROI returns.
*Test more offers, test more data, essentially you are just going to be never ending testing.

I can tell you what has worked for me.

I heavily promote PPL (pay per lead...lead generation) offers. This is because there is no credit card / purchase required. All a user has to do is fill out a form, so conversion rates are typically much higher than offers that require you to make a sale.

I favor offers that have a make, get or save money benefit to them. This is what has overall worked best for me and they tend to have the greatest mass appeal (will be of interest to a large general audience). So the potential exist to generate high volume and they are fairly easy to cross promote on the back-end.

Some of the verticals that I have done extremely well with are: insurance, education, loans, debt, credit, assistance, mortgage, discount offers, homeowner offers, etc...

In addition to the above examples that don't fall into the make, get, save money angle. Promoting website signups (dating for example) can also be very profitable. I have done just as well with dating compared to the other verticals.

Free trials + S/H can work well. Weight loss is pretty evergreen. You really need to promote what is hot...For example, what is Dr. Oz talking about? You ideally want to promote something with a $50+ (the higher the better) value and the user can get for like $5-$9 S&H.

I promote a "very limited number" of products. I would stick with the above before trying to promote products, making straight up sales is harder. To make the same ROI or at least close, you need something that has mass appeal then it also has to be one of the following... 1. unique / not available locally. 2. something that the user can buy at a true decent discount. 3. solves a house is on fire type problem.

It's important to test offers within the same vertical. As there will be times when one offer will significantly outperform the others. When you find the best ones, it's a good idea to have access to them from more than one network. Networks will sometimes cap the amount of leads you can produce or they have a fixed budget for the month for how much can be produced. So if you hit a cap or the network runs out of budget and the offer gets paused. Then you can just switch to another network and keep producing.

I've been promoting CPA offers for over 16 yeara and I have generated an insane amount of commissions / ROI by sticking with the above. Granted, there is so much more that goes into it and the above is really just the tip of the iceberg. As you still have to deal with data acquisition, inboxing / spam folder problems, testing, etc, etc, etc...

Anyway, hope that helps some.