I am surprised that it has not yet been mentioned, but although I love Astia 100F, it is not the best choice of slide film when it comes to learning dead-on exposures. It certainly has a wider exposure latitude than Kodachrome 64, as well as other slide films, and it is way too forgiving in unfiltered mixed lighting situations compared to other slide films. It is almost as if it has more modern technology in it than some film that was last updated several decades ago! ; )
So while I think Astia 100F is amazing, I would not use it with the primary goal of learning correct exposures. Also, from the few bracketed rolls of 120 Provia 400X that I have shot, it, too, seems that it has a slightly wider exposure latitude than some other slide films. If someone knows of a film with less exposure latitude than Kodachrome 64, please let me know because I would not mind fine-tuning my meterless metering using my brain. : ) Perhaps an older emulsion like Ektachrome 64 (Japan Only, but a few rolls left in America), Ektachrome 100 (recently discontinued), or Ektachrome 100 Plus (a little pricey)? I do not know, since I have not yet shot any of those emulsions.
Once you have exposure down, I would suggest trying out Astia 100F indoors and Velvia 50 and 100 outdoors without people (the 100 when you need a little more speed, and not the 100F). Ektachrome 100G is nice for product photography (so controlled lighting there). I also use Astia 100F in 120/220 for outdoor portraiture (wonderful film).
Remember that you should not be afraid to go against your meter's reading because you are the photographer, and you know what the correct exposure should be once you are comfortable shooting low latitude slide film in all kinds of situations. Best of luck! : )