Welcome.

And remember: It's not the bike that makes the biker. It's the other way around.

Building a 150$ commuter was the best thing I could have ever done for learning about cycling.

If you can afford expensive bikes/components, go for it. But remember, the risk of theft increases...

As for practicing, there is nothing better than to simply commute to where you want to go by bike. Cycling 30km a day taught me how to be an efficient and safe bike commuter. Even though it was on a beater bike - the best knowledge comes from experience. Become one with your two-wheeled machine. Take it wherever you want to go. No ride is too long or too hard. Eventually, 10-15km commutes are a joke.

It's becoming more clear to me that cycling is the easiest and best form of transportation if you live in the city and don't need to carry out furniture or any other large items.