Do you know you can change your bridge officer's skills to whatever (almost) you want? So if you want an engineering officer that can create a turret AND shield, you can. Just look for the skill trainer in Earth Space Dock. Granted, he is a little hard to find since his office is tucked away under Admiral Quinn's office.
On the ground, science kits are either focused on healing or buffs and offensive. For an offensive science kit, try slotting Electro-Gravitic Field and Exothermic Induction Field. The first roots and slows all opponents in an area, the second sets them on fire. They'll try to run but becuase they are rooted and slowed, they can't easily escape. Its a nasty combo.
In space, the staple skill that just about everyone uses is Tactical Team (TT). I usually keep two copies of TT running. Be sure to have some shield heals (Science Team, Emergency Power to Shields and Transfer Shield Strength) as well as some hull heals (Engineering Team, Auxiliary to SIF and Hazard Emitters). And as you approach level 50, you will find that you are often facing multiple opponents at once. That is when area attacks like Beam Fire At Will, Torpedo Spread and Cannon Scatter Volley become very useful.