The vast majority of projects in the Minecraft sphere are "FOSS" - Free & Open Source Software. As such, they usually only have the developer(s), plus sometimes a handful of additional helpers for support. Here's a guide of how to get support.
This "guide" is based off my experiences as a support helper for some large FOSS projects, as well as inspired by a similar blog by Madeline Miller.
Try to find the answer yourself
Before even looking for the support channels, make an effort to solve the problem yourself. Look through the project's documentation (Especially the FAQ), there's a good chance someone's already encountered this problem, and shared how to solve it. This is one of my biggest peeves, as probably 90% of the support requests I reply to are already documented.
Asking your question
Find the correct support channels
Most projects have many places where they can be contacted (i.e. marketplace reviews, an issue tracker, Discord, etc.). Generally they have a preferred place to be contacted for support requests, another place for bug reports, etc. Take the time to review their page, and see where the correct place is to ask for support. In addition, if the project uses Discord for support, make sure you use the correct channel.
In almost no case will direct messaging members of support staff be part of support. See also Don't Mention
Don't "ask to ask"
Messages such as "Can anyone help me?", "Anyone here?", "I need help" etc. all fall under "asking to ask". Now, someone has to respond to ask what your problem is, then you have to type out your question, wasting a bunch of time. In addition, there's a sense of commitment to responding to someone asking to ask, which comes off as needy.
Include all relevant info
A lot of the time, people ask for support with an error message, but then don't include the error message. Again, this results in back-and-forth to get the error message, wasting time that could have been spent helping you if you'd included the error in the original message. In addition, have other possibly relevant info like logs, configs, etc. on hand in case they need that too.
In just about every FOSS project, the developer and any additional support staff are unpaid volunteers. As such, there's a good chance that everyone may be busy, sleeping, etc. when you ask your question. Expect to be waiting up to 24 hours for even an initial response.
Mentioning someone ("Pinging", @ing, etc.) sends a push notification to the staff member. As with asking to ask, this comes off as extremely needy. In addition, there's often someone else who can help you.
"Bumping" means sending another message referencing the original message, usually within a few minutes of originally asking, that serves no purpose other than to send another unread. Examples include ".", "?", "anyone?", "hello?" etc. An exception to this is if your original message has gotten buried, then bumping it or resending the message is generally ok.