If you want something that is difficult to kill, succulents are your best bet, very little water needed and they have some beautiful varieties, my favourites to grow are things I can eat, citrus trees are pretty tough and need a normal level of care, they have beautiful scented flowers and the fruit look very pretty on the tree too, I also love chillies, they are easiest if you buy a plant not seeds (the seeds can be tricky to get going) and they only need just enough water and sun