I’m a West Londoner and therefore cannot give accurate info on safe/good areas in North London but here are some websites that might interest you:-

http://www.maidavale…
http://www.urbanpath…
http://www.tripadvis…

It seems from the tripadvisor webpage that the areas surrounding Maida Vale are a bit dodgy (Kilburn, Edgware Rd).

One of the local estate agents has this write up which is probably biased to encourage you to buy property in the area:-

Enjoying a plethora of architectural diversity, styles that range from bohemian, traditional, period and modern, with, bijou, comfortable, large and positively Grandiose! MAIDA VALE has it all! Tree lined thoroughfares, cobbled mews, park squares and secret gardens, acres of communal parkland, neat window boxes and a canal, who would want to be anywhere else?

The name derives from The Battle of MAIDA VALE fought in 1806 during the Napoleonic war, fewer than 5000 troops landed on the shores of France and won a mighty battle, this so exhilarated the British, A new district was born. MAIDA VALE is a continuously evolving neighbourhood with strong links to Television and The Arts, once here, few move out. There is a popular street café culture and the urge to wine and dine alfresco keeps a relatively small community, close knit.

Outdoor pursuits are amply catered for, take your pick from bowls, tennis, athletics, swimming and much more, Dr Roger Bannister trained for his famous 4 minute mile in MAIDA VALE recreation ground.

Enjoy the tranquillity of the communal gardens which seem to go on for ever, find a quiet corner or a shady tree and you would never know how close you are to central London.