I've used ring slings, wraps, and mei tais. Mei tais are my personal fave. My advice would be: find a carrier YOU like and use it consistently, the more you use it the more you and baby will get used to it. You can use it for short bursts as you are getting used to it (maybe 10 minutes at a time a few times a day). Also, most importantly, move around as soon as your babe is in the carrier...bounce, walk, rock, whatever--just move. I think that's the single most important thing I learned from more experienced baby wearers when my first was a baby...you can't just stick them in a carrier and then sit down and eat lunch, you have to move around, that's what soothes the baby. And then when the baby is asleep, yes you can sit down and eat some lunch :) .
One of the reasons I Iove the mei tai is that (for me, at least) it pretty easy to nurse in it. You just lower the straps so that the baby is sitting at nipple level and help them latch on and support their head. I would also suggest nursing in the mei tai as a way to get your baby used to it. I almost always have to nurse DS (2 months old) when I first put him in, then he sleeps a bit, then wakes up and has some quiet alert time, just observing stuff from his vantage point. There is a learning curve to this stuff, you have to work at it to master it. When DD was a baby (she's 5 now) I did a lot of looking in mirrors when I put her in carriers to make sure she was positioned right.
Other posters mentioned twisting the mei tai or narrowing it with a hair tie so legs could hang out. Those are great suggestions.
Some people have mentioned the Baby Bjorn. When DD was a baby there was a lot of talk about how that particular carrier was not the best because it put too much pressure on the hips (I think). I don't know what the latest info on that is, I'm just passing this on as something to keep in mind. We do have a baby bjorn, which I could never figure out how to even put on (mai tais and wraps seem easier to me) but my DH uses it and likes it (he uses the mei tai as well, but prefers the bjorn). I'm just sharing that for whatever it's worth.
Basically with baby wearing you just need to practice (remember there is a learning curve, you and the baby both need to learn what works for you) and move when the baby is in the carrier.
Keep at it!