The Rabbi of my shul said that it is not considered a proper "lekicha" if one has a ring on their finger while taking the 4 minim. This is especially relevant to women who have jewelry (and men who have wedding rings).
The basis for the rabbi's statement is a gemara (Suk. 37a) where it is evident that a barrier between the lulav and one's hand does not render the taking of the lulav "lekichah tama" (לקיחה תמה). Following this, the Bet Yosef (OC 651, end) cites an opinion that men should remove tefilin from their arms and women should remove rings when taking the lulav as these would constitute a chatzizah. However, Rema (OC 651:7) states that this is not halachically required and is only a chumrah.