In my opinion, slings can aggravate shoulder injuries, I opt for a more "spread the baby weight evenly carrier."

Some that come to mind:
* wraps - if your new at using a wrap, having one with a bit of stretch is helpful, otherwise the woven wraps (Gypsy Mama, EllaRoo, Storchenweige, etc) are best for support
* mei tais are great, easy and can be worn in front and back (BabyHawk, Kindercarry, AngelPack, etc)
* soft structure carrier- like a mei tai but with buckles. My favorite is my Mama By Design, I also have a Beco.

You could try out http://www.mamatoto.org or The Babywearer for more specifics of carriers, pictures and how-to's.

Happy babywearing

I use a Mei Tai (BabyHawk) for longer wearing periods where she won't be in and out frequently. It can be a lil more comfy than a sling.