Record Details and Keep Evidence of the Incident

Write down all the details of the incident as soon as you can including descriptions of the perpetrator(s), clothes they wore, any distinguishing marks, any nearby vehicles or witnesses, and anything they said such as homophobic/transphobic abuse or threats they made. 
Take photographs of any damage to property or your belongings, such as graffiti, or damage to your car.
If there are any witnesses, ask them for their contact details and ask them to write down what they saw, sign and date it, as soon as possible.

Keep any evidence safe, such as clothing, photographs and letters/notes. If the perpetrator may have left fingerprints somewhere, do not touch the area, let the police know.