One way to raid...
Raiding -
Tick one - Send 2 (or more, if the enemy has good sensors or a high sensor SS they will prevent you getting reports, is why your scouting corvettes need lots of stealth) scouts on spy mission to your selected enemy planet.
Tick two - Send your fleet to the enemy planet (the more stealth your fleet has the less chance it has of being detected, throw a few high stealth ships in with your main fleet) and send two more scouts on spy mission to the planet.
Tick three - Send two more scouts to the enemy planet on spy mission.
Tick four - You will receive the spy report from the first spy mission. On the spy report you will see how many ships are present and how many are incoming, if you see their entire fleet or anything more than 10 ships present or incoming change the orders of your main fleet to "Spy Mission", your main fleet will scout the planet then return to where it came from not engaging. Do not risk losing your fleet, 10 good stealth ships can trap a fleet, if you have 20+ very high sensor sniper cruisers (always travel with at least 5 of these) you may clear them out but not worth the risk. If there are no or just a few ships there let your fleet attack and send two more scouts in on spy mission.
Tick 5 - Your fleet will attack the planet (if you haven't spy missioned out), know that they will probably have shields so don't expect to do too much damage on this tick. Check the spy report for incoming ships, if none stay on the planet, if you see any incoming ships move your fleets back to a safe planet within your empire (this is important - Do not go to attack another enemy planet from an enemy planet, is way too easy to trap a fleet doing this, go home and start again). If you stay on the planet send two more scouts on spy mission.
Tick 6 - On this tick you will start killing the eco and maybe take the planet depending on your fleet size and on how many shield generators the planet had). If you take the planet go back to base, make sure that you start sending out scouts to the next target so that you can start again. If you don't take the planet stay for another tick if the spy report is clear.
Tick 7 - Repeat the process, send scouts etc.
IMPORTANT - If at anytime both scout missions fail get out of there or Spy Mission back home.
This method will guarantee the safety of your fleet and you will slowly destroy there eco.