How do you feed a stray cat?

I live in an apartment complex and there is a stray cat in my neighborhood that I always see out at night and in the early morning, it is always huddled up under a car. I am thinking about adopting it or at least finding it a good home but I wanted to start by leaving food out for it, I bought some Purina cat food and a bowl, but I was wondering how I could leave it outside where the cat can get to it? There are always bugs outside and I was wondering if that is harmful to the cat if it gets in the food. Thanks for your help ^_^