Cloak can be very useful but very problematic if used wrong.
Basically you want to get your ships about 6-7" away from their target when you decloak, and then pop out and nail them.
If you play the Eagle ships, they are basically eggs armed with hammers. The Battlehawk gives you 6 plasma dice and 4 phaser-1s for 120 points, and the King Eagle is a cheap command ship at 175 points, but you'll have a delicate fleet.
The Klingon hulls have all the bonuses of Klingon hulls maneuverable, doubled forward shields, with the extras of cloaks and plasma torpedoes.
The Hawk ships can take a lot of damage, have good shielding and lots of phaser-1s and 3s. You don't need cloaks on the Hawk ships, but they're nice to have.
However I'll say this - the dreadnought that you want to use is the KC9R. It's tougher that the Condor and has the same maneuverability as a Federation or Gorn Heavy cruiser, meaning that it can keep pace with your heavier ships.
I've not seen a solo Romulan fleet (rather a Klingon-Romulan allied fleet). Basically you want to get a target, knock it's shields down with plasma torpedoes and if it isn't cinders when they've finished firing hit it with phasers.
If you are firing your torpedoes then the enemy fleet is going to be firing it's phasers at your torpedoes, which can give you a nice uninterrupted phaser barrage.
Drones are not your friend though, and they are particularly nasty for Eagle ships, which only have a couple of phaser-3s to swat them with.