How to stop smudging lead

Ok so I’m using Fabre castle 900 pencils and whenever I use the darker ones, 6B,4B,2B, the lines don’t like smudge but there’s always like a tint around the lines. Like it looks like I’ve shaded stuff in near it and there’s like an area around it where I obviously put my hand and it’s not awful but like every hour I have to go back and erase all around my drawing to get rid of the smudge. Do I just gotta change my technique, is it the pencils, is it the paper ( I’m using a strathmore sketchbook), like what should I do.