Tactical: Fill all slots with the best consoles you can get for your energy type. (e.g. Phaser Relays for phaser, AP mag regulators for AP etc.) As an escort, DPS is essential, so your tac consoles are the most important.
Science: Field Generators are by far the most useful general science console, especially for escorts which have lower shield modifiers.
Engineering: I use these slots as my dump for universal consoles. Borg Console is generally considered a must. If you want to maximize critical chance, you can plop a Zero Point console in there, and if you can afford one, a Tachyokinetic. Remaning slots can be filled with a mixture of Neutronium (all energy and kinetic resist) and Monotanium (best kinetic resist) armour consoles. As an escort you shouldn't find you need to use any RCS consoles.