This paper presents how a range of suitable strengthening method can be selected from the vast number of existing methods via a guideline. The guideline considers the structural system, type of problem and relevant circumstances. In the guideline, only methods that can be considered as new and investigated in the project Sustainable Bridges are at this moment introduced. However, the guideline can easily be updated with additional methods and systems following the same suggested approach. Furthermore, the guideline's precision in suggesting strengthening methods can be improved by use of future experience from real applications and development of different strengthening methods.