If I had a time machine, the first thing that I would do, would be to travel forward in time and find out the lottery numbers for the whole of that year, then travel backward in time and continually win the lottery all year long. By this time I would have billions and would never have to work ever again, I would be set up for life!.
But, this alone would not be enough for me, with all of my newly aquired billions, I would travel forward in time, buy a massive laser-gun, and a space-ship and bring them backward in time with me. This would have three great benefits, firstly, it would be great security for my house, secondly, world-class scientists would pay millions just to look at them, and thirdly, a space-ship is much faster than a car.
When I have collected enough money from the lottery, (approx. 1 trillion) I would take my money, spaceship, and laser-gun backward in time to the middle-ages, where I would easily take over the world, because all they have for weapons are swords, and spears. Also, I would be able to predict things from the future, so the people of the countries that I am taking over will beleve I have super-natural powers, and will not fight against me in fear of me using my 'powers' in order to take over.
Finally, I would travel forward in time, (to my origional time) where I would be known as the ruler of the world, and would also have all the luxuries of the 21st century.