Twitter sentiment analysis has been explored in various domains including Business reviews, Political forecasting, decision support, Movie reviews and many more. The nature of data collected by Twitter imposes several challenges for sentiment analysis. There are other factors also like the selected classifier, multiclass sentiment analysis, feature selection method, number of feature selected, level of preprocessing, preprocessing techniques involved that can affect the accuracy of classification. This paper discusses various factors affecting the accuracy of Twitter sentiment analysis. Consideration of these factors can be very beneficial while designing an efficient classification model for twitter sentiment analysis. The survey also focuses on various metrics used for representation of sentiment analysis result and their relevance.