To work in projects means to work on a defined goal with a strong focus on quality and costs. To reach this goal in the best possible way, project organisations have to be flexible and fast moving. To that effect, decisions are on the daily agenda in projects. To make a decision the project team, the project manager and project stakeholder have to work together and follow the process of decision making. Identifying the problem, collecting alternatives, score the options and decide: This is the common way of making decision. This paper was collecting relevant parts of decisions in projects by making interviews with project manager. The research made it possible to name this six factors: Human factors (emotions, cognitive and motivational processes), leadership, information, subject of the decision, cost/quality/time and patterns. Basic essence of this paper is: Keep it simple! Decisions are important and must be carefully considered. But the effort for the decision itself should not be higher than the consequence of the decision. Good and easily prepared information, short and scheduled meetings and a high level of acceptance of the team can affect the success of a project significantly positive.