The task of routing data from a source node to the base station is a critical issue in Wireless Sensor Networks (WSNs). Fuzzy logic is the main proposal of a number of papers in the literature as an effective method for making decisions to transfer data towards the destination. Although fuzzy logic has a very important role in designing routing protocols for WSNs, identifying its fuzzy sets and defining best possible rules is a complex challenge. This paper introduces Improved-fuzzy logic (I-fuzzy), a simple and effective method that helps to address the weakness of fuzzy logic in terms of defining rules. The Ifuzzy method is tested in several scenarios by using GloMosim simulator and compared to a classic fuzzy logic approach and to a traditional minimum hop routing. The results show that the I-Fuzzy method outperforms the other approaches in terms of data delivery, energy conservation and load distribution.