Selling clothes online poses some challenges for those who buy them and for those who sell them, they are products with which people still feel the need to have a physical contact. Some of its attributes are not easily communicated digitally as the fit and the feel of a fabric. Besides, the lack of standardization of sizes practiced by the clothing industry results in a scenario that raises several doubts to the consumer/user. The objective of this dissertation is to elaborate guidelines that may contribute to the design of more efficient, effective and satisfactory female e-commerce websites, thus providing a positive user experience (UX). Some methods and techniques were used and sorted into two stages: an exploratory and a descriptive research approach. The exploratory research consisted of an exploratory interview, an online questionnaire and an interview with fashion specialists. It was possible to verify that the biggest problem faced by the consumers/users when buying clothes online is related to sizing and the wearability of the pieces. In addition to being a usability problem, by inducing users to errors, it was noted that its greatest impact was on the user experience as it can creat a negative expectation regarding the interaction with the system. To carry out the descriptive research, the users were divided into two groups and asked to do a usability test on a selected e-commerce website in order to evaluate their interaction when buying clothes. One group used a desktop/laptop and the other a smartphone. At the end of the test, the users were asked to respond to a debriefing and the AttrakDiff2 questionnaire. Finally, the data was analyzed and the tasks carried out on the two devices (desktop / laptop and the other a smartphone) were compared in order to evaluate if there were differences in the UX. It has been found that there is a lack of technical knowledge on the part of the user regarding the attributes of clothing, the users do not know how to identify fabric types and they feel extremely insecure about the size information provided by the retail companies. The website fails to communicate these attributes in a way that facilitates the understanding by users and that follows their mental models. There was no significant difference in UX when comparing the interaction on the two types of devices. At the end of this dissertation, there is a list of guidelines elaborated with the objective to improve the UX on female fashion websites.