visible and kissable.
1) Airway clear
The most important thing to remember when wearing your baby is to ensure that baby's airway is clear. Regardless of carrier or carry, you should always be able to get two of your fingers under baby's chin. (This is the same for car seats, bouncers, swings, etc.) This is why we discourage reclined carries because it's harder to keep baby's chin from falling onto her chest cutting off her air way. The only time a reclining position is recommended is when baby is feeding.
2) Close Enough to Kiss
Regardless of carrier or carry, baby should always be close enough to kiss. This allows you to monitor baby's breathing at all times. This is always important but especially important when wearing a preemie.
3) Always visible
Baby's face should always be visible to you the wearer. It's ok if someone looking at you can't see baby's face, but you should always been able to see her.
Additionally, always be aware of your surroundings when you are wearing. Make sure that baby isn't able to reach for something like a knife or hot stove, especially when on your back. Never wear baby while riding in a car or on a boat. If you would wear protective equipment while participating in an activity, it's not an activity to do while wearing. Always make sure you are using an appropriate carrier for baby's age and size, and practice new carries over a bed or couch until you are comfortable.
These are the biggest safety concerns, but for a more exhaustive list, see this wonderful post by Babywearing International.
When in doubt, ask. We love answering questions in the Facebook Group.
Safe and Happy Babywearing!!!