I'm trying to create a Sentiment Analysis algorithm for a custom data (government dept specifc data) and not like any other social media data etc. The data exists but I need to categorise the data as positive or negative.  My requirement is to classify the test data as positive or negative using a sentiment analysis algorithm. The big challenge for me is to take the similar set of government data which I can get. But I need to prepare the training data set. For this I need to classify the training data set as positive or negative. On what basis do I need to categorise the data set as positive or negative. The reason I'm asking this question is that preparing a good training data set is very important to improve the accuracy of my sentiment analysis algorithm .I have come up with my sentiment analysis algorithm but really need to prepare a robust set of training data(classified as positive or negative). Experts - I'm a newbie to the machine learning area and I need advice from the researchers and experts out there. 
How to create a training set and classify them as positive or negative
sentiment analysis