“What kinds of responses do you want when you're complaining?”
Don't respond at all. Sit and reflect upon your current situation and how you could possibly change it for the better to meet the need of people like me around you. I'm not complaining purely for my own benefit. Recognise that not everything needs a response. Just because you can respond doesn't mean you fucking should.
If you're unaware if I want a solution or help, ask. Do that first and always. I don't know why this is never something that people don't do. If something doesn't start with a clear call for assistance, it might be a good idea to ask if someone wants help... Especially if what they're doing seems like venting frustrations. Your “assistance” is only going to make that person more upset, and you're more likely to get a more receptive person if you ask “Do you need help?” or “Do you want help?” or something than if you just blaze on in and solve their problem without consider what the purpose of their complaint is.
Solutions that involve “just go buy this thing” aren't useful and don't take into consideration a person's financial situation. If part of your solution includes “just go buy this thing,” especially when that thing is quite expensive, it's only going to make someone angry.
Stop individualising everything. Start reading things to see if it's an infrastructural or systemic problem before you go telling someone what they, on their own, can do. Otherwise, you're contributing to the same things they're already complaining about.