This attack strategy can be used if your town hall level is 6.
My main strategy:
Wall breakers: 6
And the rest are archers.
Healing spell: 2
Castle troops: Anything depending on the mercy of other clan members.
Choosing whom to attack in multiplayer battles:
Basically, I don't attack just for the sake of cups. I prefer the highly lootable ones. First I check the loot available, then the position of castle and air defences.
If castle and air defences are not near to the outer walls, I usually avoid them.
1. The castle troops:
I use an archer to bring out opponents castle troops and destroy them using a troop of archers around the defence troops.
Note for valkyrie: Give enough distance between each of your archers so that she gets killed before she even starts rotating and kills most archers.
2. Giant attack:
Use giants near the air defences to destroy them. Deploy one giant initially to check for any springs. Then deploy them all. And then the wall breakers as needed. Be ready with a healing spell if any wizard tower is near by.
3. Balloon Parade: (As the hog rider calls it)
After the air defence is gone, deploy balloons near the archer towers(so that they get destroyed first). Once you release the balloons, get ready with healing spell as you need to use it as soon as you see an air bomb popping up.
Deploy the archers as soon as you the defences of a side going down. Remember to deploy at least one archer to the corners if anybuilder hut is there (you might lose your third cup just because of a builder hut).
Use single giant to divert a wizard tower and attack it from any other side by a group of giants.
Use wall breakers as diversions to archer towers.
6. Use castle troops when necessary.
Wizards: Avoid using wizards unless you have them in good numbers and have the support of a healer.