Stop and search was used extensively to the point certain areas you had a 100% chance of being stopped by police. Mandatory prison sentences and length of sentences were tripled. Gangs and members were mapped and the information made public so there were no claiming ignorance or protection once you were caught.
After sentence there was a lot of intensive work to extricate gang members out of the culture and those who wanted them back in the gangs. Scotland was very different to London though, it didn't have the whole aspirational element to it in being a gang member that comes with teh music, media, women and money that London does.
This is a very simplistic summary, Akala makes a much more coherent and comprehensive summary of the policies they enacted in the video posted above.