Many of my edits fall into a few general areas; this seems to be true for edits made by other people as well. If people who ask questions on ELL would simply heed a few simple guidelines, the site would be a more enjoyable and useful place for everyone.
Proper capitalization
The words “I” and “English” always use a capital letter:
ELL is where i go to get help with my English. (incorrect)
ELL is where I go to get help with my english. (incorrect)
ELL is where I go to get help with my English. (correct)
How to punctuate with terminal punctuation (i.e., a period or question mark):
Put a single space after, but no space before, these punctuation marks:
This is the first sentence. This is the second sentence. (correct)
This is the first sentence . This is the second sentence. (incorrect)
What is my question? (correct)
What is my question ? (incorrect)
How to punctuate with commas and colons:
Put a single space after, but no space before, these punctuation marks:
This is the first part of the sentence, and this is the second part. (correct)
This is the first part of the sentence , and this is the second part. (incorrect)
That leads me to this question: How can this be? (correct)
That leads me to this question : How can this be? (incorrect)
Note: there are special uses for the colon that break this convention, such as time (7:30 PM), Scripture references (Matt. 7:12), mathematical odds and ratios (3:1). Some dictionaries also put a space before a colon to differentiate between the definition and the example usage:
word (noun) a message; news : I was afraid to leave town in case there was word from the office.
How to punctuate with quotation marks and parentheses:
Put a single space before the open quote, and after the close quote, but no space between the quotation marks and the words within the quotation:
Meaning of the phrase "on the radio" (correct)
Meaning of the phrase" on the radio " (incorrect)
Meaning of the phrase " on the radio" (incorrect)
These same rules apply to parentheses as well:
The radio is on (but I can't hear it) (correct)
The radio is on ( but I can't hear it) (incorrect)
The radio is on( but I can't hear it) (incorrect)
How to offset quoted material and example sentences from the rest of your question:
On Stack Exchange sites, use a ">" character at the beginning of a line to put material in a "quote box". Notice how, in the bad examples, it's harder to tell which part of the question is actually part of the question. In the improved examples, the quoted material looks like this:
This is how to offset quoted or example material.
Bad example:
A friend of mine said this, and another friend laughed, but I don't understand why this joke is funny.
I kept wondering why the train was getting bigger. Then it hit me.
Improved example:
A friend of mine said this, and another friend laughed, but I don't understand why this joke is funny.
I kept wondering why the train was getting bigger. Then it hit me.
Bad example:
He had a problem with me.
He had a problem over me.
Which preposition is the correct one to use?
Improved example:
He had a problem with me.
He had a problem over me.
Which preposition is the correct one to use?
Other helpful hints:
You can force a line break if you put two blank spaces at the end of a line:
Here is Line 1. Here is Line 2.
Here is Line 1.
Here is Line 2.
When typing, both of those look the same, except the second one has two blank spaces at the end of Line 1:
Also, when asking about a certain part of a long passage, it's also good to put the part you are asking about in bold print:
Poor example:
I'm wondering about why the author used a hyphen in cross-purposes:
Life is infinitely stranger than anything which the mind of man could invent. We would not dare to conceive the things which are really mere commonplaces of existence. If we could fly out of that window hand in hand, hover over this great city, gently remove the roofs, and and peep in at the queer things which are going on, the strange coincidences, the plannings, the cross-purposes, the wonderful chains of events, working through generations, and leading to the most outre results, it would make all fiction with its conventionalities and foreseen conclusions most stale and unprofitable.
Improved example:
I'm wondering about why the author used a hyphen in cross-purposes:
Life is infinitely stranger than anything which the mind of man could invent. We would not dare to conceive the things which are really mere commonplaces of existence. If we could fly out of that window hand in hand, hover over this great city, gently remove the roofs, and and peep in at the queer things which are going on, the strange coincidences, the plannings, the cross-purposes, the wonderful chains of events, working through generations, and leading to the most outre results, it would make all fiction with its conventionalities and foreseen conclusions most stale and unprofitable.
In short, the better you write your question, the more time people can spend writing a quality answer (as opposed to spending their time trying to figure out what you are trying to ask).
Also, we will have trouble attracting more people to ELL if the site is replete with sloppily-formatted questions.
If I've left out another commonly-encountered problem, feel free to add your example in an answer.