Anyway I can play this hand better? I'm a new live player so my betting sizes were off. I wanted to go 1/3 on flop, think I shoulda went 45 maybe. I think 10s shoulda folded on flop especially with 3 behind him, but then again these players were pretty bad.

1-2 400 cap; 7-handed; 142 eff; hero HJ red Jacks
Limps to me in HJ, I raise to 15, SB, BB, UTG, LJ call

Flop (75) [Qh Js 8c]
Checks around to hero, bets out 20, SB calls, LJ all in for 36. Hero and SB both call. (Betting not reopened).

Turn (183) [Qh Js 8c Ks]
SB checks to me, I jam for 91 eff. SB calls.

River (183, 182 side) [Qh Js 8c Ks 9c]
SB shows pocket 10s for a rivered straight, LJ said he had kings, but makes no sense? maybe meant he had a king

Why did you want to go 1/3 on the flop?

Preflop probably needs sized up a bit. With multiple limps in front $15 is the smallest I would go, something around $20 is probably better. This depends on how sticky opponents are after limping and varies widely at 1/2.
As you note, flop bet needs to be larger. You have a set but this is a wet board, any two random high cards have something on this board. With that many opponents I would go $50 or just open shove. You only have $111 on the flop so a shove isn't too big and any bet obviously commits you to the pot.

On the flop villain's call is pretty speculative but he does have a pair and you bet small. Fold would be better because of the number of people after him but if you had been heads up I wouldn't say his call was bad. Once he is open ended he has too many outs to fold when you jam for half the pot. Yes hero could have AT and he is drawing for a chop but if hero has KQ he has lots of outs.

I go $50 in this exact situation. If I had a bit less left behind, I would shove. If I was deeper, I'd go $60 or $65.

I would bet flop 40 with a plan to jam turn.

If you are going to bet small, bet 18 (and not 20), so you can reopen if LJ shoves.

Losing a hand doesn’t mean it was played badly.

But if you wanted to win the pot, I would recommend shoving and showing your hand to avoid people calling with worse next time.

LLSNL players will tend to fold if they can see that they are behind.

snarky and not-helpful posts like these should be removed.

doesn't really matter what OP bets on the flop or turn, he's so shallow he can GII easily, no other way this was going down, just bad luck here

make it 20 pre and bet 3/4 pot.

but yeah you were going to lose anyway.

Huh? It’s literally the only helpful post in any of the replies. It actually gets him what he wants, which is to win the pot.

Middle set is always an opportunity to get value from top pair. Size up flop

Yeah, like everyone said, raise bigger pre and flop.

OP’s bet sizing on the flop got a call from TT, which is pretty awesome. Given the stack sizes, seems very reasonable to bet small and let villains do stupid things.