I need to work on my body language skills then. Is there any sources you recommend that provide good tips?

My problem is that I wear glasses, and have weird hayfever-like symptoms so when I walk in the cold to a shop, and then enter the warmer shop, my eyes start watering, which doesn't look attractive lol. My voice sounds less deep, and I do act noticeably more nervous. I need to somehow work on that, I assume it's just approach anxiety.