Attack:
Revolt to British
Refrain from using Saboteurs/Commandos in WW. They will be most likely killed by a Landmine/Spike Trap before being able to make an impact
Make sure, you don't allow generals spawning from a fort, unless they are sluggish compared to your forces
Check the troop combinations that your 5 star attackers are using, and give it a try to test the same combination yourself.
Protect and Betrayal tactics do help you the best when used properly near the beginning of the battle. Dont Betray a ht in the mouth of an ATG.
Do not neglect gattling and machine gunners, they serve you the best, when entering a base and fighting the forest defenders.
Use the Weapon Blessing if you can - it can turn a 3 star attack to a 5 star one with ease - thus getting back the diamond for sure.
Deploy your troops diagonally to the TC when going for the QV. Use a path to the TC over destroyed buildings, there will be definitely no traps on the way.
When attacking Global Age opponents don't forget to take into consideration the Resistance Chapters the defender could have researched from the Library.
Learn to see the difference between an empty and a full Bunker.
Control your forces, don't let them spread all over the base. Use raid as much as possible. Try to raid on a safe, near and easy reachable place for your troops
For countering heavy central bases (TC in the middle surrounded with concentrated defensive buildings) - Learn the Merry-go-round technique: Go in for the TC, get out to a safe place (let your troops heal) and go around the base on the wall perimeter
You don't need more than 5 regular tanks for 5 staring
Play a lot, practice makes the master
Defense:
Don't overprotect your TC when high on valuable resources. It's better to lose the battle (and getting a PT) as to lose high on resources with defensive wins.
Make sure, your opponent will attack from the Embassy or Alliance gate side in WW. The defending troops might hide behind the massive TC building
Create Kill zones in the area leading to your TC (concentrated traps) reachable from mortars and a redoubt.
Create more smaller compartments for valuable buildings, but be careful - closed compartments with defender producing buildings must have gates (best directed towards an implemented kill zone)
Symmetrical bases might be nice, but don't give any helping hand to your attacker. Make it confusing to read as much as possible.
Analyse your defense log, check where the attackers are usually deploying and implement changes accordingly (at least a few slow down traps).
Use your war base instead of your standard normal base when not too high on resources - your attackers will show its weak points.
Learn to count map tiles. The range of an artillery/howitzer is 5. The best distance of a mortar from an outer wall is 6 tiles
Don't put defensive buildings on the edge of the map, they will be most probably destroyed in one sec after the battle start, or will not join the the battle when it matters the most.
Use your Acropolis! Try to place as much as possible defender producing buildings (and Ambush Traps!) into its range.
Each area with a Tank Depot shall be controlled with an Air Defense and Tower(s).
Use the Tower Blessing each time you log out!