I'm mostly posting this here for my own quick referencing, but perhaps you may find it informative.

By the way, the word THAT is a sneaky word. It takes some writing experience before you realize just how sneaky it is.

In most cases, when you use 'that' as a pointer, make sure there's a person, place, or thing right after it.

'That' can be dropped if the verb leads right to a noun (action to people, place, or thing):

· The children claimed an ice cream break would help them study more effectively. 

· She insisted she wasn't responsible for the houseplant's untimely death.

Yet, if another word is added between the verb and the noun, the word 'that' is likely needed:

· The kids also said this morning that a television break would enhance their studying.

· She admitted begrudgingly that she might have contributed to the plant's demise.

***If time is an element, then 'that' may be required:

· The advisor announced that his report would be posted soon.

· They acknowledged that they were hampered by the lack of funding.

As a rule of thumb in questionable cases, remember: Using "that" is never really wrong, though it may be unnecessary; omitting "that" in some cases indeed may be wrong.

Keep in mind that different countries can have different preferences – kind of like the age-old debate between British vs American usage of the English language.

Change the word:

The entry fee has doubled, and that means I won't be going this year. (Most editors will encourage you to rewrite the sentence. Replace it with 'so', or some other word. Or change it: I won't be going this year because the entry fee has doubled.)
 

Don't mix up 'that' and who/whom or which:

· The man that delivers our doughnuts was late this morning. (should be who, not that).

Confused about who/whom? You can often omit it - The man delivering our doughnuts was late this morning.

Don't let a comma touch 'that' (there are a few rare instances where it is needed, but they are few and far in-between). If a comma really wants to touch it, consider if the word which might be a better replacement.

The hotel, which has the softest beds, is the Comfort Inn.

The hotel that has the softest beds is the Comfort Inn.

The Fact That - This is an evil one that makes many editors grit their teeth.

The fact that the music was so good kept me coming back.

It's really better to reword these since most publishers don't like using 'the fact'.

The music was so good, I kept coming back. OR. I kept coming back because the music was so good.

Now that we finished that lesson, I'm sure (that) we can all agree that the English language has far too many details that we need to remember.

(And considering there should only be one 'that' per sentence, the above sentence should have made someone groan.)