Basically if you make a Suggestion thread you need to do a few things.

Be descriptive (but K.I.S.S. or keep it simple stupid)

Don't echo old ideas (asking for shard buff or return, or winmillion 5star is this)
----------------------Exceptions are new or innovative ideas on these (such as a full description of what your idea for this old problem is)

Be short enough to get your point across, we aren't going to read a huge page, most likely we will skim it over or ignore it.

Don't be stupid (think about item/enemy balance before suggesting it)(think about possible copyright infringment; mario/link costumes).

Be ready to answer questions, take criticism, and suggestions. (some ideas will get torn apart so don't suggest (if you do, don't be hasty about posting, please think before you hit that button) if you have sensitive feeling).

Know what the community is up to (if people are hating on costumes ATM don't suggest it until it dies down).

Don't get discouraged, an idiot with a camera may not take good pictures but he may stumble across a really nice one once in a while.

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Why am I doing this?
A mixture of pity for those who get torn apart despite having a decent idea (5star winmillion variant threads), and frustration at the masses of unfinished, long, and simple threads and the OPs unprepared for the slew of questions that come their way.