When shade matching the first thing you have to figure out is what your undertone is. There are four main undertones red/cool/pink,neutral, warm/yellow/gold, olive/green. To best understand what undertone you are you can look at pictures online of different skin undertones. Once you know what undertone you are you want to try out different shades (lightness and darkness) of that undertone. Based off of what you describe yourself as I would probably consider you as a light medium or medium skintone depending on the brand. Your foundation in my opinion should be a mixture of your face,neck,chest color. We have multiple shades in our skin but the foundation that blends into the skin without it looking obvious is a good enough match. I understand that makeup stores can often not be the most hygienic but most foundation is in a pump so definitely try to grab a couple of disposables to do swatches on your face. Maybe you could also bring your own brush or blender to try on foundation at the rest of your face to make it more hygienic? To be more hygienic eith concealer just pump the foundation that matches on the back of your hand and match the concealer to it. Hope this helps!