First you need to come to terms with the problem: an inevitable, irreversible state of decay. This is the first part of what will happen when you are dead and in your grave. It is a problem without a solution. Just accept that. You can slow things down, and talk yourself into being okay with it, but it does not matter, you are dying already. 
Alcohol
If you drink enough you simply will not care about growing old. It just will not matter. The sense of life slowly seeping out of your pores with every passing second will fade away and you will be as unconcerned about aging as when you were young. Alcohol brings you into the moment, allows you to forget past and future and be here, now.
Being an asshole
Just by having enough experience with people and relationships you should have learned how to hurt feelings effectively. You also know that you have nothing to lose. Being able to make others genuinely miserable with the things you say helps to alleviate your sense of helplessness in the face of death by making you feel powerful and superior to them.
Going crazy
Remove all your inhibitions and do pretty much anything you feel like doing. All there is left to experience is death. It is coming soon. If you think seriously enough about your death, then nothing else matters. The approval and sensibilities of those around you are insignificant, the rules and obligations of society are likewise minor considerations.
Being kind, helpful, and using your life-experience to help others
Bullshit. They have no interest in hearing from you and are basically just waiting for you to get buried so they can pick through your belongings like old women at a yard sale. To them you are a useless old husk whose value is in your possessions. Most people need to suffer to learn, so good advice will go unheeded.
