Try to feel out the author’s intent so that you can use the software effectively, or understand why it is the way it is fully. Knowing some of the culture is helpful in this.
Don’t take things personally. This is software that pleases its authors, and for all the talk of taking over the world, the best bits are the ones that please their authors or are culturally useful.
If it breaks, see if you can fix it. Got an error message you want to know what it means? grep and the source are your friend. It’s not that scary. Just look. You might figure it out on your own. You’ll have more respect from those you ask if you don’t figure it out, too.
There’s great tools for getting an idea how things work. Use them. Want to know for sure where a process is looking for a config file? strace -e open theprogram will tell you authoritatively. If your software has the option to install debug info, gdb beomes really useful too. If you start persuing the problems you have as if you intend to fix them, you will get quite a lot of respect — and help. You won’t be seen as a leech, and that’s a good thing.
Talk to people. If you have an idea, sketch it out clearly and send it on to the author. If you find a bug, talk about it. Understand whether it’s a technical problem, expectations problem, interface or library. Those are valuable things to know in a discussion.
Accept that a few things suck pretty universally: Network setup scripts, modem drivers, and many pieces of cheap-ass hardware. Also, for reasons of manufacturer stupidity, 802.11g cards and many printers are broken by design. Don’t expect them to work. You get what you pay for, and that it works in Windows is an accident. They usually don’t work well there either. Spending a little for quality hardware is a wise investment. Open software just makes the choice a little more obvious.
Remember that a lot of people do this for their own personal gratification — some like helping others. Some like to code. But their time is theirs, and asking them to help you, specifically, as if you are the most important thing in their life might be asking a lot. This list is about how to be important enough to matter. It’s not hard — most hackers love to talk to smart people — but if you look like you just want to take answers and not share, you’ll have better luck trying to squeeze information out of a rock.