Hi,

You determine good raise sizes by using outs and pot odds, and remembering key sizes for table play. I'd suggest taking a look at bronze articles and take some time to understand these concepts :

Mathematics of Poker: Odds and Outs
Mathematics of Poker: Implied Pot Odds
Here you have 2 clubs in your hand and there are 3 clubs on the board, which means an opponent with 1 club in his hand actually needs one of the other 7 clubs in the deck (out of 46 cards left total) to outdraw you. The other 39 cards won't help him.

39:7 ~ 5.6:1, which means you need to make sure your opponent doesn't get more than 5.6:1 pot odds to make the call, or he will be able to outdraw you for the right price.

Here he needs to call $0.14 more to win a pot of $0.37, so he's getting 37:14~2.64:1 pot odds, which is low enough for him to make a mistake by calling.

Unless he thinks he can take more money from you once he hits, and that's where implied odds come in. If he thinks he can extract $1 more out of you on later streets when he hits, he is actually calling $0.14 to win $1+$0.37, for ~137:14~9.8:1 pot odds, making it a hugely profitable call in his eyes.

At the table you usually want to make something close to a potsize raise to give around 2:1 pot odds to your opponent, so that his call is almost always unprofitable unless you pay him off way too easily on later streets, which you shouldn't

A pot size raise in this spot is you putting the $0.08 in the pot, and then raising the pot size, which is $0.07+$0.08+$0.08=$0.23 at this point, for a total of $0.08+$0.23=$0.31 bet for you. Thus the $0.3 raise suggested by the others.

Hope it helps.