I like that perspective
I guess by lighthearted, it could be something like doing a reading for friends on the spur of the moment? A situation where you wouldn't want to bring the atmosphere down with a really deep reading.
I'd say you might want to memorize a couple of small spreads with carefully thought out positions that are less likely to produce "negative" results. Glass Owl's
The Way of Tea spread is one possibility I've used that produces insightful results while leaving the querent with positive things to employ in their lives. I'm sure there are plenty of others in the Tarot Spreads section that would also work.
Then practice a lot with how to handle cards like the 10/Swords in those positions, and in general seeing the "better" side of all the cards.
A lighter or more fanciful deck could also be helpful in cushioning messages. Even really dark readings don't look as threatening when you're using something airy-fairy like Shadowscapes or somewhat silly seeming at first glance, like the Kilted Rubber Chicken tarot. (Both decks are excellent reads for me, but Shadowscapes does pad its blows with all that soft, sensual, watercolor art, and the Chickens are so goofy looking that even Death & the Tower are easy to take.)
Or carry an oracle deck instead. I have a friend who's not ready to take the messages she knows I get from Tarot, but has started asking me to draw from the Faeries' Oracle. The messages aren't any less blunt, but they're in a format that she isn't as prone to overreact to when a card is less than all sunshine and roses.
