Basics, basics... Link in my sig for skill point allocation guide. Inside this guide is a link to PeterVetinari's excellent Ship Power Calculator.
Got em both? Good, read on...
Full weapons and shields is doable. Heck, my effective power levels are 100/100/50/40. More than enough for most occasions and if needed, I can drop a Emergency Power to jump either weapons or shields up to and beyond the 125 cap.
Designing for it requires a lot of math and precise skill point expenditure.
However, cruisers have less shields than science ships (sometimes even less than some escorts), but waaaaay more hull and crew to repair that hull. So, shields aren't the only leg on this table.
You'll have to consider hull tanking as well. Risky, but the rewards are worth it.
Take for example two powers commonly in use by some cruiser captains on both Fed and KDF:
Auxiliary to Structural Integrity Field and Auxiliary to Inertial Dampeners.
Both offer huge hull +resists.
One is huge hull heal, whilst the other increases maneuverability and adds resists to snares and holds.
Both run off Aux.
Now are you seeing a pattern here? This is why most cruiser captains run with an EPS console as well as armor consoles and the like. There will be times that you'll have to shift power from a system to Aux, drop the Aux power, and shift back. Having an EPS console helps in this regard.
Aux to Damp is also how some KDF battlecruisers somehow out turn a Fed cruiser and unload cannon fire on them.