Time Traveller's Cheat Sheet

In case you get stuck and aren't back further than late 1500's, acquaint yourself with the lineage and changing names of the lawfirm Thomson Snell & Passmore, the oldest continually operating law firm in the world. Write a letter to someone you trust, to be delivered at a specific date in the future, and leave it in the safe keeping of the law firm.

Of course you can't tell yourself not to go back in time, because time loops & paradox etc. So, the instructions should direct a trusted party in the particulars of how to rescue you. After you've setup the necessary details of a financial arrangement to take a small sum of money and enjoy compound interest for a few hundred years and turn it into a fortune by the time you arrive back in your own time.

Travel one hour into the past, and you will instantly die in the vacuum of space.