Defect prevention (DP) in early stages of software development life cycle (SDLC) is very cost effective than in later stages. The requirements elicitation and analysis & negotiation (E and A&N) phases in requirements engineering (RE) process are very critical and are major source of requirements defects. A poor E and A&N process may lead to a software requirements specifications (SRS) full of defects like missing, ambiguous, inconsistent, misunderstood, and incomplete requirements. If these defects are identified and fixed in later stages of SDLC then they could cause major rework by spending extra cost and effort. Organizations are spending about half of their total project budget on avoidable rework and majority of defects originate from RE activities. This study is an attempt to prevent requirements level defects from penetrates into later stages of SDLC. For this purpose empirical and literature studies are presented in this thesis. The empirical study is carried out with the help of six companies from Pakistan & Sweden by conducting interviews and literature study is done by using literature reviews. This study explores the most common requirements defect types, their reasons, severity level of defects (i.e. major or minor), DP techniques (DPTs) & methods, defect identification techniques that have been using in software development industry and problems in these DPTs. This study also describes possible major differences between Swedish and Pakistani software companies in terms of defect types and rate of defects originating from E and A&N phases. On the bases of study results, some solutions have been proposed to prevent requirements defects during the RE process. In this way we can minimize defects originating from E and A&N phases of RE in the bespoke requirements engineering (BESRE).