You'll want to bet enough to give him the improper odds
to call. At the same time, you don't want to bet too much to get him to fold a draw because you're losing value for your strong hand. Honestly, the whole "He's on a draw, bet a lot and make him fold!" or "You should've bet more to make him fold instead of letting him catch." type of talk is so stupid. You don't want draws to fold, you want them to call. And finally, your decision depends on stack sizes. Or, rather, effective stack sizes.
Lets say you're in a hand with TPTK and you suspect your opponent is on a flush draw. There is $30 in the pot. How much should we bet to give the opponent improper odds to call?
If your opponent is on flush draw, they need to get at least 4:1 pot odds
or better and make a profit. So, it'll be a mistake* for you to just bet $10 into a pot of $30 because they'll have to call $10 to win $40-correct odds.
So, you'll want to bet more but not too much more to make to fold immediately because you'll lose money. Say you're trying to decide on betting between $15 or $20. You can bet $15 into a pot of $30. They have to call $15 to win $45 or 3:1 pot odds. If they missed the turn, you've just increased your potential pot by $15 with their call. What if you bet $20 and it's too much for them, so they fold? You won the pot but lost out on an extra $15 they would've called for improper odds.
It also depends on your effective stacks. If you're both 100BBs (.50/1) deep, then bet the $15 into a $30 pot to give opponent only 3:1 odds. Say they call and pot is now $60. You can bet out $25-$30 on turn to give them impoper odds to call on river at 3.4-1/3-1.
However, what if you only have $20 behind after betting $15 on flop and getting called? Now the pot is $60, you bet out $20, and they have to call $20 to win a pot of $80 or 4:1. So, by allowing them to get to the turn, you give them the right odds to call and also see a free river since you're all in. If this were the case, then you're better off making pushing it on the flop to give them the improper odds to call. The pot is $30 + $35 (you shove) = $65. They need to call $35 to win $65, giving them 1.86:1 to win, which is exactly what they need (36% to win by river). However, you're still a 64% favorite at this point and if they miss the turn, their odds of hitting on the river drop down to ~20%. However, your flop shove might get them to fold on an even money call, especially if you think they're going to fold to a $20 bet.
Also, it all depends on who you're playing against. Most average players aren't thinking about pot odds or if they're getting good or bad odds for their draws. Most of the time, they're thinking "How much is it?" and "How much money can I win or lose with this hand?" If they're not the thinking type, but the "gotta draw, better call" type of player, than inflate the pot as much as you can knowing they're going to call you, especially in a cash game when you can rebuy if they get lucky. Just be prepared to give it up as soon as it hits.
Now, if your opponent is a thinking player and is always looking at pot odds, implied odds, never call if they aren't getting the right price. They're a bit easier to play. Say it's $30 in the pot and you know betting $10 gives them proper odds to call, but $15 give them bad odds, so they'll fold. You might want to bet $11 or $12, still improper odds, but it might induce a call because it's close enough...then again, if they're really deep thinkers where they're thinking about implied odds, then betting more would be the right choice. Again, most average players don't think like this.
Finally, if you're 1st to act, don't get fancy with the check-check/raise traps. It's just stupid and you're risking giving your opponent a free card and you're losing value for your hand by not betting out against opponents who call on draws.