I think two important considerations are list health and personalization.
List health: Far too often, I see clients go the route of purchasing lists from vendors. Do yourself a favor and avoid this outdated, ineffective, and dangerous tactic. Also, consider activating a re-engagement program to all leads who are inactive for more than 6 months. This will keep your database clean, providing better analytic insights and improving deliverability.
Personalization: Use targeted messaging. One of the key benefits of using Marketo is the ability to send triggered emails based on activity. This gives you the opportunity to reach out to a prospect based on their web activity, increasing likelihood of conversion and staying top-of-mind. Also consider using segmentation and snippets to create customized, dynamic content.
Everything mentioned above is fantastic and completely on point!
One item or tip that I think is a must have is an email launch checklist. Whether it is creating a new program or just sending a one off email, having a checklist to go through prior to launching (ensuring the To and From fields are correct, or making sure your not blasting the whole company with the 5,000+ out of office replies) will save you a lot of time, anxiety, and those cute dog oopsy emails you have to send out for the wrong content.
There are lots of different checklists out there, but Scott Wilder published one a few years ago that we still use today. you can find it ---> Email Checklist
Use humor to your advantage. Put it into your content and use that as the first piece of your nurture campaign. People will interact with something funny and lighthearted and then anticipate your next email. It's a good way to become a habit for people and it will make your brand stand out.
We put a big emphasis on our database health and making sure that all lists are clean and accurate. We're a year into our implementation so looking at the different ways we can optimize all the Marketo features: dynamic content, segmentation, etc.