I am very self-conscious when working outdoors, just in case some stranger looks over my shoulder. But in practice if you find a quiet corner this is a rarity. Most people don't notice you or are just far too shy themselves to interrupt you anyway. But when there are a few others working close by it gives you more confidence.
Make things easy
When working outside make things easy. You only need to do rough sketches at first and you can always take a photo to help with a painting at a later date. The big difference is that you have been there, picked your view point, actually experienced the light and the dimensions of a space for yourself.
Included below are a few very loose pencil and wash sketches I have made this summer. Tools used are, a tiny watercolour brush, graphite stick, charcoal, Paynes Grey, perhaps a white pastel plus a small bottle of water. I don’t spend very long on each one as I am looking just for shapes and the essence of a view (anyway, I lack the attention span to do anything more accurate or detailed).
So to recap, if you are new to working outside, do rough sketches, nothing fancy or too detailed. Just think of your sketches as brief notes and you won't go far wrong.
PS: if you have any sketches or paintings done out of doors this summer send them to me and I will include them in a later entry.