Hi,
I use 4 separate accounts. The first is for personal stuff. 2nd is for Webmaster stuff. 3rd is strictly buisness.
The 4th and most important is for junk. When you advetise online, sooner or later you'll get SPAM, usually lots of it. Use the 4th email when submitting to advertisers. They say they wont give out your email addy, but chances are they will.

Set up a web hosting account which allows unlimited (or several hundred at least) domains to be hosted on the one account. Each domain will show as a TLD e.g. yourdomain.com. HostMonster is an example. Cost is usually under $100 per year ($6-8 per month is common).

A host account like this will also allow multiple email addresses for each of your domain names ($8-10 to register a domain per annum). It's professional to promote products and offering support using your own domain names, preferably related to a product line you want to promote.

For enquiries about other products you might want to promote or see how they are promoted, open a few free accounts with GMail. You can filter out spam more easily and abandon them if necessary.