Formal:
* "How do you do?" (This was a common greeting, even for friends.)
* "Good morning/afternoon/evening."
* "Pleased to meet you."
Informal:
* "Hiya!" (short for "How do you do?")
* "Well, hello there!" (often used with a bit of playful surprise)
* "How's tricks?" (a casual way to say "how are you?")
* "Top of the mornin' to ya!" (Irish-inspired, but common in the US)
* "Say, hey!" (casual and friendly)
* "Listen, honey/sugar/sweetheart/pal..." (followed by what you want to say, indicating you're getting someone's attention)
For a more playful vibe:
* "Well, I'll be a monkey's uncle!" (an expression of surprise)
* "Hot diggety dog!" (exclamation of excitement)
Remember: Slang can vary by region and social group, so the best way to get a feel for the 1930s is to watch films from that era, listen to music, or read books set in the time period.