[Isura]

Bet sizing is kind of a black art. There are balance reasons why a certain bet size is fundamentally sound. Like 3/4 pot when deep stacked so you ensure you get allin by the river without overbetting.
But in a typical small to mid stakes games you can be much more creative and not give away anything really (actually you gain a lot of EV in spots). Balance is not super important. And furthermore you can achieve balance by varying bet sizing. Really think about the bolded part. Like on the river given a certain betting pattern it makes sense to bet 1/4 pot with your whole range, or maybe you're whole value range.

Ask yourself,
What do I want to accomplish? Do I want him to calldown light? What sizing will encourage a float? What sizing induces bluff raises? How does his range react to different bet sizes? How does his range react on different board textures to various bet sizes.

Dissect their range and how they react to different situations. Make them think. Most players don't want to think too much. Put them in unfamiliar situations, whether it be overbetting, tiny river betting, etc.