In my first machine learning project, I built predictors for the Iris Dataset in Python, combining decision trees, entropy and a neural network, with my ID3 decision tree frequently averaging over 80% accuracy.
The predictors performed well, especially considering it was my first instance of making them. Testing early and often was a significant factor in the final success of the project. If I did it again, I would record the accuracy after each method was added, to show how much each one contributed.