There are plenty of dodgy resources and websites out there (known as Essay Mills) that may appear legitimate at first, but are nothing more than pirates offering to plagiarise your essay for you and take your money for their trouble .
Here is a list of ethical sites that may assist you in your studies:
Enhanced Learning Educational Services (ELES)
Fantastic study skills resources & study skills sessions for secondary schools.
Tips and tricks to help you plan your time, study, and handle stress.
University of North Dakota
Student Success Centre is easy to navigate and has a number of excellent study resources.
Prentice Hall Student Success
Tonnes of interactive information to help you study
Plagiarism dot org
This is a really useful and comprehensive collection of articles and information on plagiarism.