Ask Not "How Are You Doing?"

I think a lot of information is contained in the tone of the response, even if the words are just "fine." Think of it as a conversational calibration. How much of a hurry is the other person in? Are you giving each other full attention? Are the emotions generally positive?

In business contexts, I like to answer positively, quickly, and without reciprocation. Sets the right tone.

See this post [LW · GW] for an in-depth analysis of what's actually going on with "How are you doing?". (the fact that it's not actually a question is a feature, not a bug, in it's primary use case)

That said, I endorse "what have you been thinking about lately?" as a question to ask if you actually want to start an interesting conversation.

I often use "What are you up to?" as it seems more natural and can be used almost in any context.

It should be noted that this is not true in a large number of other cultures / languages. Because it is the standard greeting here, 'How are You?' is part of call and response rather than a question, but in places that haven't standardized on it, it is a genuine question.

Honestly, I find it awkward to have questions that aren't meant to be actually answered too.

I often do stop at "hello". I also sometime use "what ho!" or other archaic/amusing variations.  But most of the time some form of "howzit / how are you / how's it going" is a lighweight conventional conversational handoff to let them know it's their turn to speak.  

In many conversations, a more direct/specific question would be offputting and unhelpful.  It adds pressure to be clever or informative, and takes away options to remain brief and lightweight ("fine.  you?").  I'd prefer most social contacts to start out with this negotiation - each participant has an opportunity to inject important/urgent topics, and only if both pass do you push harder for a non-urgent discussion topic.

Note, this is all rationalization, not rationality - I've had bad luck with trying to start conversations more quickly, and this is my reasoning for why that is.  I'm sticking with simple, short, ambiguous/meaningless introductory phrases (mostly - there are LOTS of exceptions.  Don't be boring on an early date, for instance - your goal there is to seem interesting and find topics of mutual conversation quickly.  

I like "what's the most exciting thing to happen to you recently?" as a replacement/follow-up to how are you - I find it often sparks interesting things

I hate the greeting.

Sometimes, an honest answer feels like a social gaffe.

Depending on your situation, more like always an honest answer is in fact a social gaffe.

"What are you doing?" often means "what are you thinking, why are you doing that thing? That's wrong." At least to my ear. 

I prefer to start higher bandwidth conversations with "what have you been thinking about recently?".

I think I would have agreed that answering honestly is a social gaffe a few years ago, and in my even younger years I found it embarrassing to ask such things when we both knew I wasn't trying to learn the answer, but now I feel like it's very natural to elaborate a bit, and it usually doesn't feel like an error. e.g. 'Alright - somewhat regretting signing up for this thing, but it's reminding me that I'm interested in the topic' or 'eh, seen better days, but making crepes - want one?' I wonder if I've become oblivious in my old age, or socially chill, or the context has changed. It could be partly that this depends on how well the conversationalists know each other, and it has been a slow year and a half for seeing people I don't live with.

Sometimes you already [know] what someone is doing. (at one level)

These drawbacks are all limited. In my experience, it’s almost always more effective to ask “what are you doing” rather than “how are you doing.” If you retain this habit over time, you may experience more enlightening conversations and a slightly enlivened social life.

And perhaps the times when you ask 'how are you doing' will be slightly more impactful.

If 'what are you doing?' generalises, I'd say people would end up answering just the same way people answer to 'how are you?' or 'how are you doing?'. In fact, in Spanish '¿qué haces?' or in Greek 'Τι κάνεις;' (both literally meaning 'what are you doing?') can be used, depending on formality and closeness, as greetings, and the usual answers are as shallow as 'fine'. In other languages, 'where are you going?' is a customary greeting and again it's not expected to be answered with an honest description of where you're physically going to, but rather with another more or less fixed expression similar to 'fine'.