I'm not a tactical genius by any chance, but this 442 has been working incredibly well for me, it holds it's own on both ends of the pitch against any kind of team. Other facets of the game like man management, training and set pieces are just as important to me to gain an extra edge. As for the positions:
SK - Just the standard goalie, as long he's not a terrible passer
WB - This is where i have my best full back, Grimaldo, and this role allows me to utilize his skillset to it's fullest. He's told to stay wider as he's the attacking outlet on my left side.
BPD - I got great ball playing defenders on the likes of Otamendi and mostly Antonio Silva, playing from the back allows them launch attacks very efficiently.
DC - This is where i put my best jumper, as they are my set piece magnets. My 2 options here, Verissimo and Morato are also quick and capable of dealing with a lot of situations in both the ground and air.
FB - Here I have a very physical and tenacious full back, Gilberto. He's not allowed anything too fancy and he covers the flank while the winger in front of him does his thing.
IW - This is where I would place my best passer. He's told to take more risks and he uses the 'cuts inside with ball' instruction to place himself behind the strikers in the AM strata and play balls into them.
DLP and BBM - Any player that plays these roles must be able to defend well. I place the DLP(de) on the left to cover for the WB's forward runs. This pairing has worked very well to me.
W - A standard winger. I have not been able to utilize this role to it's fullest yet on my team because all my right wingers have a 'cut inside from flanks' trait, so i don't know yet how potentially good this role will work out.
AF - I prefer a quick striker here, as he will be receiving a lot of balls over the top or into space, aerial ability is a bonus here, luckily my strikers (Ramos and Musa) have both.
DLF - I play a more technically gifted striker here. I use Guedes here even though he's mainly a winger/inside forward, but he's technically good enough to play killer balls to the AF and the W, and a competent finisher himself to be on the receiving end of them as well.