To vs. For

When to use TO 

1. Direction - Expressing movement toward something
i.e. We’re going to the zoo this weekend.

2. Receiving - Showing who or what receives an action or item
i.e. She was always mean to us.

3. Connection - Showing an abstract link between two people
i.e. I am married to my best friend.

4. Attachment - Showing a physical attachment between two things
i.e. The piece of paper was accidentally glued to my hand.

5. Comparison - Introducing the second part of a comparison
i.e. They preferred water to soda.

6. Reason (with verb) - Describing why something happened, when the explanation uses a verb
i.e. I study so much to get good grades.

7. Infinitives - In the infinitive form of a verb, to comes before the root verb.
i.e. To succeed in anything requires motivation.

8. Time - used to mean “before” a certain time.
i.e. Ten minutes to closing!

9. Synonym of “until” - often used colloquially as a replacement for “until.”
i.e. We’re open from dawn to dusk.
 

When to use FOR 

1. Support - Indicating agreement, allegiance, or favor toward something
i.e. If you’re not for the union, you’re against it!

2 Representation - Showing an action on behalf of or representing something else
i.e. I may work for Walmart, but I don’t shop there.

3. Exchange - Introducing the second part of a purchase, deal, or trade
i.e. He bought the entire Skrillex discography for only a dollar.

4 Length - Indicating length of time or distance
i.e. Go straight for a few miles and then turn left.

5. Gratitude - Showing thanks or gratitude
i.e. Thank you for your email.

6  Reason (with noun) - Describing why something happened, when the explanation uses a noun
i.e. She became a doctor for the money, not the long hours.
 
7. Conjunction -  a coordinating conjunction that acts as a synonym of “because,” although today it’s a little outdated. 

i.e. The crops aren’t growing, for the weather is lousy.

8. Comparisons with what’s normal - You can use for to emphasize how something is different from the norm or general standard.
i.e. “You’re not bad for an elf,” said the dwarf.

9. Scheduling - to indicate a planned arrangement in the future.
i.e. Is our D&D session still on for later?

To vs. For

Using to vs. for purpose and reason
- to is used with verbs (i.e. I came here to see you)
- for is used with nouns (i.e. I came here for you)

Using important to vs. important for
important to - indicates personal or sentimental value, with emotional significance
important for - indicates a practical benefit, not always an emotional significance

Using to vs. for with receiving something
- Essentially, when you’re talking about someone receiving something directly, use to followed by the recipient (the person who receives something).
i.e.  Every year I give a birthday gift to my dog.
- If you’re talking about the reason or purpose behind doing something—but not the actual giving—use for.
i.e. I bought a birthday gift for my dog.
(Notice how the action in the last sentence is about buying the gift, not giving the gift.)

source: grammarly blog