I was an MTT sNg player too, its a difficlt transition. Do not call all ins with just top pair That is sadly a bad play. Most of the time you want a solid hand for a shove to call.
Pot bets are usually weaker players bluffing
or semi bluffing, Check raise often when you get your spots, so when you are in a hand again, people will stop betting into you and you get free cards when you need them, or you can steal right away.
Patience is a must. More so than tourneys, in tourneys blinds are the issue, cash, your BR is the issue.
Actually pay attention. Start with the players to your left and right. Get their image, style, then after you got them go to the next 2, and so on. Do not get too into them because players come and go often.
Write a tooooonnnnn of notes! Anything you see that is worth rememberig, Pot betting the river with a great hand, with air ext ext. Remember how many times they do it i like to be like 1/1 times then if i see same play again and its different i go 1/2 if again its still different 1/3 that means it might not be a true play. But if i see the same thing 3/3 times more than likely its a solid read.
Uh.... Thats All i got, I ply mre HU now bc i love to bully players around but hope this helps GL to you, you are going to have the hardest time ajusting. Tourny to cash is hard! hahah