54 plate clio 1.1 electrics

hi everyone, I'm sure this has probably come up on here before, its the electricks on my clio, some times the auto headlights don't come on in the dark, when you switch on the headlights manually the back lights don't come on, also the left indicator tries flashing when you press brake pedal, I just dont know where go start checking earths and stuff, all advice on this would be appreciated thanks