One on One but against the odds in strength/tech....e.g Sovereign class against Scimitar
1) In-system warp far as possible away then stop.
2) Enter silent running.
3) Slowing intercept target, unable to detect, they'll be uncloaked.
4) When within torpedo range, boost power to weapons and fire a full spread of quantum torpedos at their cloaking device (since their shields should be down, this will also affect other systems like shields.
5) Unable to cloak, boost power to shields to engines, going to full red alert and fire all phasers with the torpedo tubes ready to load and fire more volleys.
Sidenote: Boost shields or redistribute then when needed during the battle.
Outnumbered/fleet
Two heads are always better than one, if you're part of a fleet and outnumbered, it's best to order all available ships to target one rather than individual, together you're stronger, separate you're weaker.