Easy and guaranteed money is buying tons of 400 coin bronze packs and listing every player, manager, fitness card, healing card. For players and managers, make them mostly 150 start and 200 buy now, though some players randomly go for 1k or more so do a quick search on futbin to see their price and then list them at that. Basically fill up your transfer list with them, and then keep relisting everyone after the hour expires. Eventually, the vast majority should sell. You tend to at least double what you put in I've found, its just a slow process though if you stay on top of things and keep relisting, you should sell everyone within a week.
There are better ways, like investing in OTW players who will get in forms, or actually playing seasons and the WL, but for easy and no risk money, definitely that. Or the random super easy SBC's that are cheap and give you basically guaranteed profit (theres lists of them on the fifa subreddit). I just find those tedious usually.
