Top 5 Attacking Strategies

Anti-turrets

The biggest danger early in the game when you are attacking an enemy base is that your weaker units (of which most of the early ones are) will get picked off by enemy turrets. To avoid this, send in your anti-turret troops first, in small groups. Usually two per turret works, but that is only if they are leveled up high enough. Once the turrets have been taken care of, you should send in your weaker troops. Also, if you see defensive units emerge from any of the buildings, deploy other troops so that all the fire isn't on your anti-turret ones. Once the turrets are down, you will have an easy route into the base.

En Masse

As the name suggest, this strategy just involves using sheer force of numbers to penetrate the enemy base. If you are going for three stars, you should pick the strongest point of the enemy base to attack. That way, when your numbers are dwindling, you will have the easiest bit left at the end. However, if there is a particularly obvious weak point that doesn't appear to be a trap, then you should attack there. Usually the enemy concentrate their strength around the HQ, so use an aerial bombardment if you have one, to knock some health off. You should still pick a good variety of units.

Note: This strategy should be avoided if the enemy has any area of effect turrets, such as Mortars. These will damage all units in a small space, potentially meaning your entire army can be wiped out with a few shots.

Split attack

The favorite of most players, this has you deploy two or more groups of soldiers at different parts of the enemy base. Ideally, you will have them close enough together that they can quickly meet up to help each other once the initial point of attack has been breached. For example, if there are two turrets reasonably close together, you would deploy two groups of soldiers so that both turrets are not focusing on a single area. If they do, your units won't stand a chance. Idelaly use a group for each turret on the outside of the enemy base. Another facet of this strategy is to hold some units back until the end to strengthen at the end of the attack.

Sacrificial

There are a few units which can take a great deal of damage before they are destroyed, and with this strategy you can use these to keep the enemy turrets busy and allow your faster units to run through into the center of the base. While the turrets are being worked on, you can quickly grab resources (pick units for this which instinctively target resource collectors and storage buildings) and damage the very center of the enemy base.

Inside job

When you are looking at the deployment screen, you will see a blocked out area showing where you are not able to deploy units. It is hard as the defending player to know exactly where people can spawn in, so with this tactic, you deploy your troops in the very center of the enemy base, or in a location they do not expect you to be able to appear (normally people spawn outside and have a walk to get to the base where they will come under turret fire).