For skin tone, look at your veins on your wrists, if they're greenish looking then you have a warm tone, if they're blue then you have a cool skin tone. <-- there's other methods, but this is the quickest and easiest way.
When picking out the shades, it's best to grab the sample (if available) and put some on your hand, walk outside into the sun and see how close it matches to your actual skin color.
Remember when buying a concealer and compact, you want the correct skin
tone and
shade for your skin.
If you're Irish, you're likely "cool" for skin tone and "porcelain/ivory" for shade.
<-- based on my experience and everyone else I know who's of mostly Irish descent
