What i need to buy for making my first g scale layout? Using LGB, Bachmann or Piko sets

The first step is a starter pack, LGB, Piko, Bachmann sells the most famous starter sets, you need to buy one like this:

This set comes with a locomotive, an oval track, some wagons and a controller, it's all you need to run your train, but you can think bigger and buy some extra tracks to make a good layout. LGB offers bronze tracks that you can use indoor or outdoor, if you don't have place to make a layout you can use your garden to run you trains.