I tend to give brief physical descriptions of characters. I prefer to show their attitudes, often via their own speech but in also in the way others refer to them. L'Evallier has a reputation for being the snob's snob and I get other characters to refer to him in this kind of way. Brankaresh, Chief Wizard, uses flattering language and it is clear early on he is a creep. I sometimes think of actors who might play my characters' roles should the Brenebourne novels ever be filmed (I wish!) but it does help me picture them better. Good pictures lead to better writing (because it comes through that I've thought the character out).
I've always loved characters that develop over time which is why Commander Vimes is my favourite out of Terry Pratchett's Discworld series.