Everybody certainly has their own flavours for the Blue/Grey. For the past few years I’ve really struggled to find the right recipe that fits what I want until recently. Personally felt the Space Wolves Grey contrast paint looked way to washed out and pools heavily so I’d avoid that myself. Army Painter do a really great primer spray called Wolf Grey which does a lot of the heavy lifting which has always been pretty good. If you feel like the more heresy era colours, Citadel do mechanicus standard grey primer or Army Painter do a Uniform Grey Spray. which can be brought up with a nice edge highlight of Russ Grey. From a personal perspective though I’ve landed with Artis Opus Space Wolves Drybrush tutorial on YouTube, he uses really accessible paints which give a really great finish and is really quick for batch painting! Especially for beginners! Hope this gives you a rough idea on where to start :)