When you are sending someone a communication requesting that they do something for you, spend a moment thinking about how convenient (or inconvenient) you are making things for your recipient. To me, text messages are a way to quickly share short spurts of information. They're great for things like telling someone you are running late. Using a text message to ask someone to do something substantive, like write a sales proposal, doesn't make sense. It is too hard to capture big projects out of text messages. If you are assigning or requesting work, I would argue that rather than send a text message, you should be writing an email (or sitting down with someone) where you can provide a more thorough explanation, giving your recipient a chance to better understand the assignment and have a nice easy platform to get it started from. Unfortunately, everyone doesn't think the same way I do and I constantly bang my head into this when someone sends me text message that requires further action.
I'm great at capturing tasks from emails and personal conversations. Whether at my desk or out on the road, I can quickly capture those events into future OmniFocus tasks. Nevertheless, I've never been good at capturing tasks from text messages. Part of it is because I just don't use text messaging as much as some people. Jumping when I get a text message makes me feel like a Pavlovian dog and if I'm busy, I may not read it. But that isn't the only reason. It just isn't easy to capture a text message. Regardless, I often find myself blowing something because someone asked me to do it to text message.
I'm trying to fix that. First, I'm making the pool of messages more manageable. I'm deleting message threads as they become irrelevant. For instance, if I have a thread between myself and Katie Floyd talking about what time we will record a Mac Power Users episode, once that thread has reached its conclusion (e.g., "Let's do it at 8 AM."), I delete the thread. No longer do I have a list of 50 or 60 threads just sitting there. The only threads I have are active ones. If there is task arising from a thread, I deal with it before deleting it.
Apple does not make this easy. There's no way to delete multiple threads with one swipe. Moreover, deleting a thread on my phone doesn't delete the same thread on my other iOS devices or the Mac Messages app. I've got individually deleted it in those places as well (again without the ability to delete multiple threads at once.) As a result, when I first decided to try this, I did a lot of swiping and tapping on all of my various devices.
The next thing I did was change my own personal habits about how I manage text messages. When I read a text message and it requires a future action, I immediately capture it in OmniFocus. How I capture it depends on where I'm at and what I'm being asked to do. I've got Siri, Drafts, or the keyboard. One thing I don't have is the ability to forward a text message to an email address, which would let me use the Omni Mail Drop service. (Update: "Turns out" you can forward texts to an imail in iOS so you can forward a text to the Mail Drop service.)
This new workflow is more work but I'm not blowing it on text message based projects anymore. What I'd really prefer however, is that people stop asking me to do actionable tasks in text messages.