Well that´s an unusual question!
Obviously it depends on what you´re cooking. I wouldn´t want to put basil in baked beans, for example, but it´s a pretty versatile herb with many vegetables. Some herbs smell very strong, others are more subtle, so that should give you an idea of how much to use.
As for spices, again,some are more invasive than others. Overdo the cloves in a pickle, for example, and it will taste like a visit to the dentist. I always think of franchises which make cinnamon rolls - mostly horrible because the rolls only taste of cinnamon. And there are spices which smell pretty wierd - asafoetida (hing), for example, but when cooked, adds a huge layer of flavour.
My advice is to use the internet: every time you cook something, just look up some combinations. "Chicken and thyme", "Pork and sage", "Beef and rosemary", that kind of thing. Gradually you will build up a flavour profile in your mind.