If you are having a baby you'll definitely need a sling. No baby should have to be pushed round strapped into a chair. Even if you use a push chair routinely, when your baby is unhappy, you will need a sling on standby (unless you ignore the tortured struggle and screams and plough on regardless). Slings leave your arms free to get on with your normal life. The most useful is the ring sling. It will be useful for years. It is easy to use, and comfortable for wearer and baby. My son (nearly 2) still uses this sling a lot. the Hippy chick is also more useful now for when we're out and about and my son wants to be given a lift.
The ring sling is easy to make: an excellent pattern can be found at sleepingbaby.net
You can buy the rings necessary for making the sling here. They are like heavy duty curtain rings.