Hope you're doing great! We all know that only relevant emails generate leads and make sales, this is why it's extremely important to segment your list and improve your targeting. Most of email marketers segment their lists by interests or products/services only, but that's not the limit. Actually email list segmentation has no limits, so I will provide you with top 5, as these are the most easy-to-use ways.
1. Geographic Segmentation
Works good for both local and international businesses. Different countries have different cultures and you need to know how to talk to your leads - know their culture, say hi to them in their language and you will gain more respect than you can imagine. This kind of segmentation also works for the local businesses - your offers may differ for local buyers and foreigners, this is how you can expand your local business to international one.
2. Industry/Role Segmentation
Segment your email list by roles and industries - you know you should talk more "interesting" to marketers than to CEOs, which need straight facts to make a decision. Contacting technical guys is also a different story - better discuss such emails with your Development or Support department to not to look awkward.
3. Content Segmentation
Content segmentation is a corner stone of email marketing - always contact your list with the relevant content only. For example, your company has two main products in two different niches, and this means two main email lists - contacting both of them with the same info would be a big mistake. Always have your lists segmented by products and service your offer.
4. Behavior-Based Segmentation
This strategy needs strong analytics, as you need to know the behavior of your subscribers - how many time he spent on your website before subscribed, how many times he visited your website before, has he downloaded your demos or trials, etc. Based on this info you can segment your list and provide your subscribers with more relevant information. For example, the one who has tried your product needs more reasons to buy - new features, coming features, strategies that can be implemented using your product and much more.
You should have special list for the most loyal subscribers - frequent buyers, affiliates, active social media fans, etc. These are the people who spread the word about you and your company - make sure they have the best and the most full information.