Welcome to this group.  There are many helpful, experienced and kind people here.  
Before you chose your breeds, some of the most important things are climate - I don't know where you live but if it is in a warm State then you need heat hardy birds - and vice versa for cold States.  Chickens do much better in the cold than in the heat, so if you are in a southern State, get heat hardy breeds.  Another thing is temperament to consider when choosing breeds.  After choosing a breed, in my opinion, the two most important things are security and space.  Make your coop 4-5 times bigger than you think you need- and this is the same for the run.  Use 1/2 inch hardware cloth on the ceiling, walls, and make hardware cloth aprons to prevent digging predators.