If you're playing
freerolls, early people are going to be loose and shoving with a face card with any decent kicker hoping for a quick double/triple up so they can coast/bully till mid way through, hell some even 9x their chips and can sit out till the bubble.
Don't follow the sheep unless you have A/A, K/K or A/K suited. Anything less and the likelihood of being sucked out multi-handed is way too high - and likely. Only shove when you're overwhelming favorite.
Sit it out, play solid poker and you'll be at the money more often than they will be.
If you're talking mid/late you need to know your players ranges, how they bet when they have something and play in position with your ranges. You're going to get sucked out. If you're in doubt, sit it out and wait for another.
https://www.cardschat.com/forum/learning-poker-57/what-hands-do-we-start-playing-373155/
The above thread has some good info in it from myself (wider range) and a tighter player specific to MTT play.
When it comes to actually laying something down it really does depend on the player and the board. Get support software and start collecting info on everybody you play with. Use notes and start spotting
tells (yes there are tells online).
Cash I don't really play all that much, so can't really help.