Nothing wrong with building opposition by BP. There are some (weak) templates in the core book.
I put 150 BPs in Professional rating 0 NPC Attributes, and around 80-100 BP in Skills, nothing over 3. Also gave them a 1 in 3 chance of having/using Cram or Jazz. That might be some tables Pro 1 or 2... I tend to do fine tweaking of Initiative, weapon mods and Armor out-fittings to really delineate those 1-2 Professional Ratings from 0, because really that's what delineates your average Joe from someone who knows, at least somewhat, what they're doing in combat.
Liuetenants I did 180-200 in Attributes, plus minor Augs (cyber eyes/ears, smartlink, low level Initiative increses, muscle replacement). 100+ BP in Skills, up to 5. Also possible drug use. Pro 3-4.
Our table tends to run hot...