Tommse is spot on, Warpstone Glow is the colour you need. Even though you are dry brushing I would still use a fine detail brush, the marine figure is too irregular to use bigger ones. Focus on the shoulder pads edges, cheek armour and ridge of helmet, top of backpack, arm/hand armour (especially fingers), top of knee pads and feet armour. If you want to knock the highlights back a little, do a wash over the top with watered down Caliban Green. I would usually then make a mix of 1:1 Bleached Bone/Warpstone Green and only (very carefully) drybrush a few edges, wherever your light source reflects heavily off the miniature.
If you want to then add another layer of depth, water down some 1:1 Caliban Green/Black (or just black, if you are in a hurry) and wash carefully along the recesses between armour sections (The shoulder pads and feet are great for this). You can use the standard Badab Black wash for this, but it dries with a very matt finish that can stand out unless you do other things to it.
Give some of these things a try and see what works for you. Make sure you post more pictures too, there can never be enough Dark Angels on Dakka