There can be several first signs of a termite issue. However, as there are different termites, there are also different signs. In general, look for several things. Weak wood or floorboards, weak spots in baseboards or trim, droppings that resemble spilled coffee grounds, mud tunnels up the side of the house or in the crawlspace. My advice, however, would be to call a professional for an inspection. Many companies, such as ours, provide free termite inspections to the general public.