I've been learning how to use a charger and have been forcing myself to use the Kelp Splat Charger, and I must say, it is very very fun. Playing defensive is a nice change of pace than running into the action. Also, a few things.
1.if someone gets too close and you dont have a charger with close range potential, ie e liters and squiffers, ya dun ded.
2.cut off ink trails so enemies must expose themselves or jump over your ink to keep moving. This allows you to easily predict where they will go for an easy splat
3. motion controls. I assume you have this already
4. Subs and specials are your best friend. Usually in battle we dont think of our subs and specials too much, just extra tools. But when you're thrown into the roll of a charger, you start to realize many great strategies can come from these specials and subs. Baiting enemies with beakons and sprinklers to expose themselves, using kraken or burst bombs in close range, using bomb rush to claim a splat zone, forcing someone open with the Wail. Suddenly these things are downright vital to your play.
Keep in mind I soaked up all this knowledge in a few days, so take this with a grain of salt. Anyways. Good luck with chargers man, I ain't a pro but I tried to help.