The following hand was the first hand in a $1.50 turbo. I'm trying to guard against them hitting the flush with my bets. How could I have played this better?

PokerStars - $1.32+$0.18|10/20 NL - Holdem - 9 players
Hand converted by PokerTracker 4

CO: 97 BB (VPIP: 100.00, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 1)
BTN: 74 BB (VPIP: 18.75, PFR: 10.42, 3Bet Preflop: 6.67, Hands: 50)
SB: 60 BB (VPIP: 100.00, PFR: 100.00, 3Bet Preflop: -, Hands: 1)
BB: 75 BB (VPIP: 0.00, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 4)
UTG: 70 BB (VPIP: 100.00, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 1)
Hero (UTG+1): 75 BB
MP: 75 BB (VPIP: 0.00, PFR: 0.00, 3Bet Preflop: -, Hands: 1)
MP+1: 75 BB (VPIP: 25.00, PFR: 25.00, 3Bet Preflop: 0.00, Hands: 8)
MP+2: 74 BB (VPIP: 100.00, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 1)

SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has A K

UTG calls 1 BB, Hero raises to 3 BB, MP calls 3 BB, fold, fold, CO calls 3 BB, fold, fold, fold, UTG calls 2 BB

Flop: (13.5 BB, 4 players) T A 2
UTG checks, Hero bets 7 BB, MP calls 7 BB, fold, UTG calls 7 BB

Turn: (34.5 BB, 3 players) 6
UTG checks, Hero bets 16 BB, MP calls 16 BB, UTG calls 16 BB

River: (82.5 BB, 3 players) 6
UTG bets 10 BB, Hero calls 10 BB

I would raise more preflop. You have one limper and it's still early position, so in order to avoid too many callers I'd make it 4-4.5 BB. Especially when it's still 10/20 (I tend to raise a little smaller in 15/30 or 25/50 BB wise).

Then your Bets are a little small, especially if you say you fear the flush and made them as protection bets (which is right).
UTG was right to draw to his nutflush with you're rather small bet and the MP caller. But even without the MP caller your bet on the turn is so small he's correct to call. However he played a poor way too samll riverbet imo (think about if you would have called a half the pot bet, probably so right?).

As played the rivercall is ok, i don't see myself folding here ever, even with one player left to act who could raise and make it ugly for you.

So: Raise little more preflop and make bigger bets on dangerous boards with 2 players

Thanks for the feedback

What bet sizings would you be using here to protect?

Raise more pre, bet both flop and turn slightly more, shove river.

This is long winded but it explains what you need to know I hope I don't have many posts but take or use the advice as you will. Generally you should be raising more pre flop, its early blind levels so you don't have a big read on the players at the table however the fact that UTG has limped from EP is a relatively clear sign he is going to be a weak player, especially at this buy in. Now you have assumed this, you should be raising more pre flop, around 4xBB+1 for every limper in the pot, your plan should be to isolate the weak player who has limped UTG in order to be playing a HU pot in position against him. The raise size may seem a little large pre flop however with the blinds so low its highly likely this UTG limper is going to call you and that you will isolate the other players from the pot. You will also be in essence extracting more value with this raise size in general and inducing the MP caller to fold, thus be playing in a heads up pot with the weak UTG limper where your edge will be bigger and you will have position.

Now post flop its clear your betting too little, with it being a multi way pot at this point, you want to extract the maximum value possible yet still protect your hand on a potentially dangerous board. The bet you fire on the flop is at best a C-BET size and your giving both players the chance to see the turn cheaply, you should be betting more to around 70-80% of the pot in this situation, you are likely to get any Ace hand to call and any 10 with a decent kicker to call, all of which we can assume to be well within both villains range, now in terms of protecting your flopped TPTK its safe to assume that the general player at this stake is not thinking about the odds they are getting to call with a flush draw or a gut shot in this situation on the flop, so protecting your hand here is going to be difficult if either villain is on a semi good draw, by betting a larger sum than you have, you are making it more of a mistake for both villains to call, giving both in correct pot odds, and leaving them in a tricky situation if they miss on the turn, at least one of them will fold their hand here now. On the turn the same as above is applicable, if you had bet larger on the flop, you could of put in a decent sized raise again on the turn of around 70-80% to gain the best value possible and if both players were still in the pot move one of off it, further if you believed that the villains would call any raise there is no reason not to bet the pot at this point on the turn and look to shove the river; as we can expect most of the time you are far ahead enough with this turn card. You should be thinking in terms of maximising value rather than what the minimum is you can bet to protect your hand. Remember micro stakes is not so much about the fancy plays as it is about relentlessly betting for value when you have the best of it. By the river, abiding by the suggested bet sizes above, if villain calls we can probably assume he has a top pair kind of hand something such as AQ OR AJ being at the top of his range ( micro stakes players do like to limp these yes) perhaps anything down to any mid suited ace, he would of been likely to re raise the turn with a two pair or set and fold any kind of drawing hand as soon as you placed your turn bet, so on the river you could shove, or bet to induce a shove. This is of course on the basis that the larger flop and turn bet sizing induces at least one of the villains to fold and you are playing in a heads up pot. In your situation with your bet sizing both villains make it to the flop, and the river is a six, which pairs the board and anyone now chasing the flush has now hit it. Its generally a dangerous card, but your never folding in this situation unless you have a very clear read on your opponent's, when UTG leads out for 10bb we can assume he is trying to get a cheap show down with his Ace or inducing you to shove against his flush. It is really a situation where more often than not you are going to be shoving with the best of it, especially if we figure in the likely hands that even the worse players are going to be limping UTG with, 7/10 times in this scenario it figures to be
a low or mid ace, the other three times being deuces or suited connectors.

To sum up:
Raise more Pre Flop to isolate weaker players seeking to play heads up pots with them ( your edge is bigger here and you have pos )

Bet more for value post flop, protecting your hand is not to much a consideration, your bet sizing here is a leak in itself, you should be taking the right lines to maximise the value you gain from TPTK hands in the micro stakes this is definitely +EV long term

Try to iso raise the weak limpers, they can be a big source of value, you can amp up the value betting against them and most of the time get them to call you down with much worse, remember your edge is bigger heads up against a fish then it is in a multi way pot where your biggest edge may only be position.