The aim of this study is to investigate ways to maximise the efficiency of tin based laser produced plasmas as sources of EUV radiation in the 2% band centered on 13.5 nm. It has been found that targets containing below 15% tin atoms by number emit more brightly in the spectral region around 13.5 nm than pure tin targets. Furthermore, if the remaining material in the target is composed on primarily low-Z atoms, then both plasma continuum radiation and Bremsstrahlung radiation are greatly reduced. In addition, if the target is illuminated with a prepulse, the conversion efficiency shows a distinct increase. The third parameter under examination is the laser power density, which controls the ion distribution in the plasma. The influence of low-Z atoms on the tin ion distribution in the plasma has been investigated and found to be of little consequence. Measurements were made in the region from 9-17 nm on an absolutely calibrated 0.25-m flat field grazing incidence spectrograph, and on two 2-m grazing incidence spectrographs. Spectra and conversion efficiency data from a range of target materials and illumination regimes are presented.