Here's my tips for setting up and using Cases.

This does not include using cases via Portal or Communities yet.

This also does not include any social media monitoring tools.

Rules

When it comes to your customers, there are no rules.

As much as you try to get people to only submit emails to your support@ or via your Support form on your website, it just does not work. People are going to email their favourite Sales Rep, Support Person, or The Boss directly. Or they are just going to whinge on Social Media. Also, people are going to add many support items in the one ticket, and they are going to respond to a closed case with a new open case. You need to deal with all of these scenarios.

Things to help are:

Create Cases by Email
Create Cases by Web. See Web to Case
Create Cases from Outlook
Create Cases from Gmail. Just get Cirrus Insight.
Create Cases using Publisher Actions
Create Cases on your Mobile device.
Clone Cases
Close Cases

Case Management Rules

Use Case Feed

Case Feed is going to be the only way to use Cases in the future, so if you are setting up Cases now, use Case Feeds.

All Cases start in the Queue

No exceptions. If the person who normally handles cases is out sick for the day, an important case could get missed because it is owned by them.

With Case Queues there is only one place that new Cases exist.

All Cases are Owned by either a User or a Queue

This isn't my rule, it is Salesforce's rule.

You Take Ownership of the Case before you modify it

If you are working on the Case, you are the owner of it.

This is a general rule and may be broken in special circumstances.

Set up

Start on Paper

Yep. Leave Salesforce alone - and go and grab some paper.

I want a simple flowchart or a simple list of statements in the form of IF this THEN do this.

I need to know what your support process is before we even start looking at cases.

It does not need to be a fancy Visio or Online diagram like this one or this one with swim lanes.

Example

Generally we like to solve cases within 24 hours.
If Case comes in by email
- Person reads the question.
  - If they can answer it.
    - They respond straight away
  - If it's for Product X
    - Forward the email to User Y
    - and CC the client.
  - If they can't answer it.
    - They forward it to the appropriate person.
    - and CC the client.

etc.

Questions

What support levels do you have?
Who are the people that handle cases?
- Do you have different teams for different products?
What is your SLA?
What happens if you can't meet your SLA?
- Do you notify the client.
Do you want an automatic response to say we have received your case? (see also Web to Case).
- What should it say?
What needs to happen for a case to get Escalated?
- Who does it go to?

Support Settings

The default Case settings page.

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Set the Automated Case User to be the Sys Admin user.
Turn off all the Portal stuff that is not relevant anymore.
I would suggest checking Send Case Notifications from System Address so users who get notification emails will be able to filter them out in their email apps, and they are not confused with emails from the user that updated the case.
The settings around Ownership may be important to you if you have Accounts and Case sharing rules so that users can only see some records.
The settings around Closed Cases is dependent on your business. Do you want to force users to enter specific outcomes when a case is closed? If so, do not enable Show Closed Statuses in Case Status Field. For quick turn around support issues, this may not be needed and you can have the Closed Status on the Status field.
See below for setting up Case Feeds.

Set up Queues

Queues are a great way to manage Cases in the initial stage. See Case Queues.

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Create the Queue

https://help.salesforce.com/HTViewHelpDoc?id=setting_up_queues.htm&language=en_US

To email all queue members, you need to set up an email address on your mail servers.

My suggestion is to not check Send Email to Members. The emails go to everyone in the queue and you don't want to bombard people with emails.

Add Users to the Queue

If you have lots of team members then set up Public Groups.

https://help.salesforce.com/htviewhelpdoc?id=user_groups.htm&siteLang=en_US

Otherwise, just add the users to the Queue.

Remember to add this to your New Staff Onboarding Procedure document.

Email to Case Setup

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Set up Email to Case. Unless you are a large organisation with an internal IT support team, you are going to use Email To Case On Demand.

https://help.salesforce.com/HTViewHelpDoc?id=customizesupport_email.htm&language=en_US

Email To Case On Demand allows for attachments up to 10MB.

Enable Email to Case

https://help.salesforce.com/HTViewHelpDoc?id=customizesupport_enabling_email_to_case.htm&language=en_US

Settings

New Case Emails

My suggestion is to not check Notify Case Owners on New Emails. It should be automatic that people log in and deal with new cases every day. The only time I would suggest this is if you have a very sporadic case load and don't need to check for new cases every day. See Case Queues.

Thread ID

Check both of the checkboxes in When sending email from a case, insert Thread ID in the following sections:

Yes, it can make your emails look a bit ugly, but it definitely helps in tracking return emails.

Email Routing

Do you have different people that handle different cases? Do you have different email addresses that need to be created as Cases? (eg productasupport@ productbsupport@)

Settings

https://help.salesforce.com/apex/HTViewHelpDoc?id=customizesupport_routing_address_settings.htm&language=en_US

Save Email Headers

Check this unless you have very tight storage requirements on your Org. You never know when you are going to need it. And you can always uncheck it later.

Accept Email From

Do you do internal support only? Then set up your domains in here.

Task Settings

I really don't know who's stupid Idea this was to create a Task as well as a Case. So, you get an email, which you have to deal with, you deal with the case, then you deal with the task to say you have dealt with the case? WHY!!!

Just don't set Create Task from Email. Save your sanity.

Priority

I don't like the idea of auto setting a priority because then priority becomes meaningless.

Case Origin

Set to Email. Helpful to distinguish emails that come from the Web. See Web to Case.

Verify your Email

Once the routing settings are done then verify the email address. This means that someone has to receive the email and click on the link in the email. (annoying if you don't have access to that email account).

Outlook

If you use Outlook (I'm sorry), then be able to create Cases from Outlook. Add the new Cases to the Queue you set up earlier.

If you use Outlook for Mac (I'm really sorry), then you are out of luck. You will need to forward emails to the support@ email address.

Assignment Rules

Assignment rules are very handy. Assign cases to different queues based on State or where the case came from.

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You have limited options with email. You might try by pre-filling the subject when linking from your website, and then but how often do people overwrite it with their own subject.

Assignment Rules also act as an Auto Responder and you can choose a different email template to send to people.

I would set up Assignment Rules to start, rather than default settings in Support Settings, even if you only have one support team processing Cases, because then it is easy to just add others.

Set up Support Processes

You will need the flowchart you worked out earlier to do this.

Set up the Page Layout

This is only for non Case Feeds setup.

Add Emails Related List to the page layouts.

Set up Case Feed

See Case Feeds

Case Management

Communicating with your Clients

Emailing

Use ThreadID

The ThreadID is used by Salesforce to link any existing emails to Cases that are emailed into the Case. If there is no ThreadID the case will be created as new, which is annoying because there is no Case Merge functionality except in a paid app. Use this formula to create the Thread ID https://success.salesforce.com/ideaView?id=087300000006trk

Respond from a System Address

The biggest tip I can give for using Cases is to Respond to all emails from a System Address.

This helps your clients not get too comfortable that they are always going to get a personal response from one person, and will hopefully stop them emailing staff directly.
Users don't have to remember to forward the reply back into Salesforce.
You can set a notification on Case Comment to go to the owner of the case. for when an email is replied to.

Depending on your business, and the way they use Cases, you may need to use Email to Case Premium, which has some extra features to handle Case Threads.

Using Quick Text

Quick Text is great, and it only works with Case Feeds.

https://help.salesforce.com/HTViewHelpDoc?id=case_interaction_using_quick_text.htm&language=en_US

Knowledge

See Knowledge