I always target the same houses on a 6 weekly basis, that way your name becomes familiar with residents.
I have had £300 jobs in terrace houses and £50 jobs in 5 bed detached so just pop one through every door regardless of size.
I stay local maybe a 5 mile radius at the most.
Good luck with the drops, sometimes you will do an area and it isnt until 2/3 weeks later you get a call so keep your chin up and keep going even, if in the short term you do not see any immediate gains.
Mark