Maximizing the business value while preserving the alignment to strategic objectives is a permanent concern of every organization. Therefore selecting the project portfolios that are more likely to convert a company vision into a business success is a crucial process. The project portfolio selection problem has caught the researcher’s interest since more than four decades and has been approached in different methodologies, techniques and decision support systems. However, there is no agreement today on a universal approach addressing this problem’s major aspects in a flexible and practical way. This paper is aiming to provide project management practitioners with a fundamental background towards an effective project portfolio selection process. It provides a detailed problem clarification and breakdown from both best practices and literature perspectives. It also synthesizes the various approaches and methods that have been so far proposed in the literature with regards to project portfolio selection. Thus a critical analysis of the most widely used approaches is presented. Furthermore, a concept of an effective project portfolio construction framework is outlined in order to guide future research in that area.