I think there are two types of people who don't post enough information to get the help they need: 1) people who think that the "experts" on the forum magically know all the answers off the top of their heads, 2) people who think that their mod is so special that they are worried about people stealing it.
For type #1, I try to educate them that experts are mostly people that are just really good at researching. Even if we think we know the answer, we usually double-check our information because programming is about being exact -- the name of the method has to be exactly right, and so forth. If I'm answering a person's question I will usually pull up the Minecraft or Forge source, pull up my own implementations, look in github, check StackOverflow, etc. to gain confidence in my answer. The most important thing for these people to know is that the problem is usually very specific to their code. It is very difficult for anyone else to know what sort of typo they put into their code, or what sort of logic error, without seeing the code. Secondly, people often don't understand that the logs usually give a very good idea of what is wrong, so teaching people to really look at the error log is helpful. In a perfect world a person who comes here for help posts all the information, but also has put in their own effort to try to understand it.
For type #2, I can only say that honestly no one here is interested in stealing other people's ideas and if you are stuck on coding then it is doubtful your mod is so advanced that it is worth stealing. But I suppose it is natural for people to be protective of their ideas, it's just that it is hard to help someone who isn't sharing.