Make sure you’re comfortable
Astronomical objects are clearer when they are higher in the sky, and the most comfortable way to observe high elevation objects is to recline. A garden recliner with support for your lower legs can be extremely comfortable. It can act as a windbreak for your back, while keeping your feet off the ground, and it provides a useful ‘rack’ or ‘hanger’ for your binocular case, charts, notebook, or a flask with a hot drink (keep this away from your optics!). If you dehydrate, your body will reduce circulation to your extremities, so drinking plenty of fluids will also help you to keep warm.