1. "Play Nice" and be a "Good Sport" - Don't go mouthing off to every rival who attacked you or raided you. You are only going to attract more attacks and raids if you act like a jerk. It is hard for rivals to want to attack you if you are being civil and nice to them. This is a war game, don't get offended if someone attacks you and steals your money.
2. Syncronize your money building collection times. Set an alarm reminder. If there is no money laying around, you are not going to be a target. If you are attacked, it is likely for BP's, unless you have pissed somebody off.
3. Bank Valor, Save Money and Wait to get the higher stat units. Don't blow it on lower stat units as they will be completely useless later and wont be brought to battle. Buy Aircraft Carriers and other high stat valor units (wait until you progress up the ranks.)
***This is assuming you already have a healthy base of low to mid level units. If you are extremely weak when you reach the whale zone at level 130+, you need to bulk up fast on mid level, low casualty money units and valor units.***
More to come...