No matter how old you are, you need to discuss death with your parents, your children (when they are older), your significant others, and any other family you feel you might be involved when you die or they die.
To learn more about death in general, and some great tips about funerals - http://www.orderofthegooddeath.com/
Here are my most important recommendations:
Have a will
Have a medial power of attorney/Advanced Directive for Healthcare or your state's equivalent
If possible have some small life insurance to cover death related expenses. Funerals are not cheap.
Service or not?
Specific religious service?
Gathering after the service?
Open casket or not?
Cremation or burial?
Do you want a green burial that is better for the environment? (See order of the good death for more information.)
Donate body to science?
Read below about digital asset management after death.
Whatever matters to you, make it known. It's uncomfortable but it will make the lives of those you leave behind simpler and will make sure you get what you want. Or in the cases of your family it will make dealing with their death less stressful - which is important when it will already be such a stressful event on its own.
General Death Resources:
and please watch this - https://www.youtube.com/watch?v=PVgumSUZQRI
When you die you leave behind a lot of digital assets, as well as things that can/need to be accessed digitally. Please consider this.
I use a password manager, LastPass which has an emergency contact configured: https://lastpass.com/support.php?cmd=showfaq&id=9972 so someone can access every password they need to.
Did you know google you can configure what to happen if your account goes idle? It's google inactive account manager. It lets you say what should occur. set this up now. They will send regular reminders of your settings. https://support.google.com/accounts/answer/3036546?hl=en
You may also want to consider telling the will executor handling your social media accounts what not to tell family. My family knows I have fetlife, other peoples do not. Sadly fetlife at this time does not gracefully or easily handle dead people you have to email them and then they will lock or delete the account. Facebook on the other hand handles death pretty easily and can memorialize the account or delete it.
https://youtu.be/hhniUz5xG24?t=6889 "Death, Dealing, and Digital Forensics"
Visit your friends, your family, or at least email them or call them, you never know when they will be gone, don't regret it.
Tell people you love that you love them.
Tell people who have impacted your life, your career, etc, what impact they had - you never know when they will be gone or you will be gone and it is important for people to know the impact they have had on the world.
Death with Dignity
Please read about the the mission of the Death with Dignity National Center - support them if you can. All states should have rules that allow anyone who wants to die, no it doesn't kill people it's a choice. I know I would choose not to suffer.
For those with deadnames, queerness, and other considerations
Look into "Body Disposition Form" within the US https://funerals.org/?consumers=legal-right-make-decisions-funeral - If you want an example of why there are examples such as the case of Jennifer Gable, who died as a transgender woman but was buried as a man by her family. https://www.funeralwise.com/digital-dying/10048/
If you don't have a body disposition form or something similar for your country or a friendly executor who knows your wishes and can speak up there could be issues as (you may be able to hire a private executor like a legally firm, or use the state) your next of kin will get to decide. If you have unsupportive family members (because of your identity or who you love) who may exclude your chosen family or deadname you or use incorrect (gendered) ceremony for you - do what you can to have a will and prevent them from doing this! (I.e. if you are unable to legally marry your partner, you unsupportive parents get to decide what happens to you, even if you have no stuff!)
High profile death
If you or a loved one is notable or known outside the family, there may be pressure from a group to know details of the death or how to grieve the death.
Try and plan, in advance, Who will post what where and how (online and off).
I.e. Will someone have access to all of their accounts and they can post a blog post that will be updated as needed and can point everyone there.
Can you afford to use an external PR agency to prevent the family from needing to deal at all?
How much detail should it include?
Can recommendations for the outpouring of death be given to direct the energy (foundation, scholarship, trust, favorite charity?)
Will there be a community public memorial online or off non close family can participate in? is there a friend of the family that is in that group that can organize that?
Educate as needed family on locking down their accounts and how to best respond to trolls. Prepare them for the mess that might happen.
So if all this is so important to me what are my choices?
I have a will
I have a DNR (Do Not Resuscitate) with my MPOA (Medical Power of Attorney)
I want organs donated and body to science.
I do not want to be embalmed.
I do not want a viewing / service, so casket moot point
I want to be cremated (whatever is not donated).
Have a memorial service if it makes you living feel better. Ideally have it with food if possible. No flowers please, donate to something like Planned Parenthood or Doctors without Borders or the Trevor Project.
I want all my online accounts purged/deleted as soon as possible (after data needed for taxes etc taken care of).
I have a password manager, LastPass, and am working to have significant other have access.
I have google auto destroy account enabled on my accounts.
Advance Directive for Healthcare (http://www.vsb.org/site/public/healthcare-decisions-day) is what you want to have in place to designate an agent in the event you're unable to make decisions yourself and also to describe what powers that agent has and, if you wish, how you expect that agent to handle things. It's a nice standard form in fairly simple language and it indicates the needed signatures, etc.
An advance directive can also be registered in a database in VA, so it's accessible as necessary. https://www.virginiaregistry.org/
The state bar also has a page quickly explaining last wills. http://www.vsb.org/site/publications/wills-in-virginia/