comma in front of therefore; semi colon in back of therefore
When you are beginning a list of irregular items
You would put the comma before the therefore. for example: I am a girl, therefore I wear make-up and have long hair. (Just an example not all girls wear make-up and have long hair.)
It really depends upon the sentence. Remember, a comma indicates a slight pause. If you would pause when speaking that sentence at that location, then put in a comma to indicate that.
No you don't have to, but it sounds better!
you don't need a comma in that sentence, since the And is a word that combines both sentences. using a comma would make the sentence look like this; you water it, then let it get lots of sunshine
Using a colon in the salutation and a comma in closing.
Yes, when using therefore, use a comma after it.I invited five more girls to my party for a total of ten of us. Therefore, my mother needed to buy more food.I was on vacation, therefore, I could not have started the fire.
You would put the comma before the therefore. for example: I am a girl, therefore I wear make-up and have long hair. (Just an example not all girls wear make-up and have long hair.)
She had one goal for the summer: to improve her tennis skills.
It really depends upon the sentence. Remember, a comma indicates a slight pause. If you would pause when speaking that sentence at that location, then put in a comma to indicate that.
You use one space after a colon or semi-colon.
Yes, typically a colon is used after "by" to introduce a list or an explanation. For example: "Please bring the following items to the meeting: pen, notebook, and water bottle."
No you don't have to, but it sounds better!
You can put a comma before or after just about any word if the sentence structure requires it. If the sentence structure does not require it, it may be permissable to use a comma to assist in clarity and avoid confusion. Otherwise, don't use a comma. Have I confused you yet? Using a comma does not depend on the word, it depends on the structure of the sentence.
Make sure you know the difference between using a comma, and using en ellipses. When you are writing, ask yourself "Is it necessary to pause, and if so, do I want to pause with a comma, or break up the sentence using an ellipses?"
you don't need a comma in that sentence, since the And is a word that combines both sentences. using a comma would make the sentence look like this; you water it, then let it get lots of sunshine
In general, no, but there are some situations in which using a comma after "but" is correct. If the word "but" is followed by an expression that needs to be set off by commas, then you would put a comma after "but" and another comma after the expression. Here is an example: I was going to say no, but, because you have presented such a persuasive argument, I have decided to allow it. An example of a more typical sentence using "but", where there is a comma before but not after "but", is the first sentence in this answer.