Older nuts won't necessarily make you ill, but their flavor will be greatly diminished. Do remember to check the freshness date if you are buying packaged nuts. I recommend storing nuts in the freezer in freezer bags or other airtight containers. The refrigerator is also fine if you are using them up quickly. Skinning nuts is an easy process.
Many nuts have thin, papery skins that are often tannic and bitter.
To remove the skins, use a method of blanching or toasting. After blanching briefly in boiling water, wrap nuts in a kitchen towel and rub in the towel to remove their skins. Dry blanched nuts out in a 325 degree oven for a few minutes. Blanching works well for pistachios and almonds. Hazelnuts and Brazil nuts can be toasted in a 325 degree oven and then rubbed briskly in a kitchen towel.