Exactly what type of clothing today requires a Shehecheyanu Brachah when wearing them for the first time?
When you buy a garment that makes you happy, you should thank Hashem by reciting the Brachah of Shehecheyanu. This garment does not have to be the best of clothes; it can be a regular shirt or pair of pants, as long as it is of some importance and it makes you happy. For clothing articles that are not special, e.g. socks, underwear, etc, the Brachah is not recited. The custom is not to say the Brachah on new shoes. (Shulchan Aruch OC 223; 3, 6) Some do have the custom only to say the Brachah for Suits since they find no joy what so ever in buying a simple shirt; if you fit this category you might do the same however the common practice is as stated above.