The book presents all the computational techniques and tools needed to start doing scientific research using computer simulations. A reader will have all the necessary basic background after working through this book, including program design, programming in C, fundamental algorithms and data structures, random numbers, debugging, up to data analysis, presentation and publishing. In each of these fields no preliminary knowledge is assumed. The reader will be equipped with a solid background such that he can perform successfully complete projects from the first idea till the final publication. For non-standard applications and further reading, many references to specialized literature are included. All techniques are explained using many examples in C. These C codes, also the solutions to exercises, can be downloaded from a Web page.The techniques in this book are independent of the field of research, hence they are suitable for conducting research projects in Physics, Chemistry, Computer Science, Biology or Engineering.There are no similar comprehensive books so far. Currently, one needs many different books to learn all necessary background. Having this book, one needs basically only a second book on field-specific algorithms in order to be fully equipped to perform computer simulations research.