I found the website linked by Beetee (esp the videos) helpful when learning how to swaddle safely.
I was hopeless at wrapping at first so used a halo sleep sack until I got the hang of wrapping using the method in the video. The halo sleepsack was easy to use and great in those early days. I use wraps or a different swaddle now and make sure that the legs have enough room to be able to move and rotate the hip joint.
The website also has good information on hip-friendly carriers. I found this handy before choosing and fitting slings/carriers.