Agree it is bad pre flop, but explain to him why.
example raising bet size is wrong for 10nl it should have been .40, raising with suited connectors in mid position in an unopened pot is not usually good, you need a multiway pot to play the suited connectors profitably
just saying preflop was bad does not help the op unless he understands why it was bad.
and the 2x 3bet was worse IMO but mistakes tend to compound
but at least the OP did not open limp with them preflop so there is a positive to his madness hehehe