The tl;dr version would be: Learn modern programming principles with a modern language, like for example Python. BASIC is kinda 80s ;).

In the end, you won't be able to dodge learning a lot of theory. You don't "learn a programming language", you learn "how to develop 'good', reliable, maintainable software". BASIC programs can tend to be exactly not that, though if you're disciplined and know what you're doing, you can achieve good results with that, too.

If you want to learn programming, I wouldn't recommend learning a specific language, and certainly not a BASIC variant. A good starting point from the standpoint of a programmer is getting a book about object-oriented programming and Python. It's a relatively simple language that makes you achieve results quickly and teach you a thing or two about good programming style and design patterns.

@Fran News: I can only talk about BASIC in general, as I have no knowledge about PetitCom or SmileBASIC. So this might be different there, it certainly is to an extent in Microsoft Visual Basic. It has certain characteristics that make it impractical for any serious software engineering efforts. It has no strict types, doesn't support handy modern "tricks" like objects, type polymorphism etc.

BASIC? Let me quote well-known Dutch computer scientist Edsger Djikstra: "It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration." Seriously, I'm sure people come up with cool stuff and it's relatively easy to learn, but gosh, it's an awful language.