I use a net only if absolutely necessary. They sort of just mosey on in and wait for a bit until I have enough water in their cups and in they go without much fuss . . . though Zucca tends to get stressed out a whole lot. He's not used to nets as much as the others.
If I'm cupping, I take it slowly. Sometimes ten minutes for one betta, five for another, twenty (!!!) for yet another. As long as they aren't stressed about it it's okay to take the time even if water changes only take five minutes. I don't like to suck them in, since it's stressful, more like they'll just swim in when they're ready . . . hopefully.
Other times, I use a net to guide them into their cups. It's the easiest method of catching without much stress. And if they do figure the 'trap' out, I just try again in a few minutes.
Afterwards, they all get bloodworms, because they deserve it for being such brave little fishies :)