I started getting C&VG from the first issue. Back then they were mainly a magazine full of BASIC listings for the Atari 800, BBC, Apple, TRS80, MZ80K, ZX81 etc. They also had ongoing tutorials on adventure game writing and the like. More bizarrely, they also had a play by mail space game, which I never played (had to pay as I remember) which featured every issue. You posted your next moves and got a computer print out of the results a few weeks later. You thought waiting for cassettes to load was slow gameplay? Pah!
For me though, it was key. I first learned programming by typing in the Atari 800 listings (which never worked first time) by checking the typos then working out 'ah, that must be what changes the colour of the border' etc. Between the monthly listings and a BASIC primer, I was away. Later on I moved onto 6502 assembler and later C once I had an Atari ST. Somehow that chain of events resulted in me writing systems generating millions in revenue for banks. Thanks C&VG!
I did stop getting the magazine after a few years but decided to submit a game I had in mind. I pulled out all the stops, wanting it to be the best Atari game they'd published. It had (ignore if you're not an Atari 8bit type) multiple DLIs, redefined character sets, sprites, assembler subroutines and all sorts of twiddly things. I then went and bought an issue to get the address to send my masterpiece to. Arse, they'd stopped doing listings several issues earlier. :-(