HKD

There really is no best tactic when playing multiplayer games because you almost always have to adopt an assertive strategy in order to win.

A good defensive starting off strategy would be to build up your defenses and make sure no enemy ships get into your base (they will wreak havoc in the early stages of games if you have no defenses). You should have one construction ship start building a dilithium mining facility and have the other one start building turrets and a few sensor arrays in places where the enemy is most likely going to strike first. Build a research station asap and research detection grid first. Sending a scout vessel around your base will help you fish out any unwanted visitors. Building turrets early is a good defence against those people who like to "con rush", which is a more aggresive strategy. If you build too many turrets or turret fields(roughly at least a quarter of the size of your computer screen), then people may label you as a "turret farmer" and you will become disliked for it.

"Con rushing" is basically sending one or both of your construction ships into the enemy base at the beginning of the game in order to keep that person on the defensive. If you do this, start harvesting one or two of their dilithium moons and if have a shipyard up and running asap. The enemy will either have to waste dilithium by making ships to attack your fortified position or build turrets to surround you. Either way, you will make your enemy waste dilithium and prevent them from getting off to a fast start in online games, which is vital. This strategy can either turn out very good or very bad. If you manage to gain a foothold in the enemy base, then that enemy will most likely be the first one eliminated from the game. If your construction ships get destroyed before gaining a foothold, then the enemy can then go on the offensive and they may turn your strategy back against you. This is a good strategy when playing against the borg, for they are weakest in the earliest stages of the game. People who are the romulans can get the most advantage if using this strategy.