Allston-Brighton is generally a safe place if you don't mind seeing the occasional drunken hooligan on weekends. It has a large college student population, so criminals of opportunity - burglars, pickpockets, petty thieves - exist. Peak seasons for them are any time students are moving in and out - May and September. Allston-Brighton also has its fair share of panhandlers and drunks - and not just the students.
Late at night, it's a good idea to travel in groups until you know the area. Calling for help is relatively straightforward. However, due to recent budget cuts by the Boston Police Department, response times to 911 calls are significantly longer than they used to be, in some cases 15-30 minutes for police or ambulance response.
Allston-Brighton also has one of the best martial arts schools in America, though you'd never be able to tell based on the building's appearance. The Boston Martial Arts Center (http://www.bostonmartiala...), located at 161 Harvard Avenue, offers self defense classes six days a week.
In addition, Emerald Necklace Budo Martial Arts (http://www.karateinboston.com/), a traditional karate dojo, is also in Allston, featuring karate and self-defense classes for adult men and women. Jason Gould, the Chief Instructor at the Emerald Necklace dojo, is a certifed R.A.D. Rape Aggression Defense instructor, and one of the founding members of Allston's Ringer Park Crime Watch.