For this Achievement you need to collect only 20 Magazines. None of them is missable, you can alway go back and pick them up.
There is no need for another Video Location Guide for all Magazines , but I dislike Videosolutions, so I created a Interactive Map for Fallout 4. So you know where there are, and can explore/search them for yourself:
https://fallout4map.de/c14x - Astoundingly Awesome Tales
10x - Covert Operations Manual - Each issue makes your sneaking better
11x - Grognak the Barbarian
10x - Guns and Bullets - Each issue adds +5% critical damage to Ballistic weapons
3x - Hot Rodder - Each issue unlocks a Power Armor custom paintjob
2x - La Coiffe - Each issue unlocks a new hair style
9x - Live Love
9x - Massachusetts Surgical Journal
5x - Picket Fences - Each issue unlocks a new item for your settlements
5x - RobCo Fun - Each issue unlocks a new Holotape game
5x - Taboo Tattoos - Each issue unlocks a new facial tattoo
8x - Tales of a Junktown
9x - Tesla Science Magazine
3x - Total Hack - Hack Turrent, Spotlights and Protectrons
5x - Tumblers Today
5x - Unstoppables
9x - Wasteland Survival Guide