There are several good ways of learning, practicing, or keeping your CW 'fresh'. All of them require that you listen to CW being sent. The 'how it's sent' can be 'live' on the air, and various and assorted methods involving 'non-live' listening. Whatever is most convenient for you is the 'best' for you. Personally, I think that 'live', on the air, is the most productive. It also get's you used to hearing/making 'goofs' and compensating for them.
Once you learn CW, that organic 'code reader' between your ears will always be more accurate than any other type of 'code reader'...
- 'Doc