Great words 
The best advice which I will give to all the 18 year olds is that please save up some money at the end of the month even if they are pennies. It will help you to get some amount in your hand after a year or two, and you never know when this money would help.
That is some meaningful advice mate…and hope that you follow these advice yourself too
Save 1 10th of your pay
To be frank, the advice I would give 18-year old me is so extensive a comment here wouldn’t be enough to encompass it.
When bitcoin comes out buy as much as you can 
Recently I am more interested in dogecoins than other cryptos. I hope that they move in a positive trend in the upcoming days. Eagerly waiting to see their performance.