How to think about practising and role playing?
Well, what does it mean to be good at an RPG? Basically, it means that, by your presence at the table, other people have a good time. As the DM you create a setup and run it so that the players have a good time. And as a player, by your actions, being proactive and thoughtful, you make it so that the DM and other players enjoy themselves.
Creating a detailed and intricate campaign setting means nothing if the players don't enjoy interacting with it. Getting your PC to level 20 doesn't matter if you're an arsehole and stop being invited to play.
So practice in the context of RPGs isn't really about getting good at the skills involved - doing voices, lateral thinking, puzzle solving, drawing maps, whatever - although those things all help. Instead, it's about being a better person. More engaged, more considerate, more amiable, more interesting and interested.
That's a good recommendation to take part in a hobby if ever there was one.