"Raise your rates" is excellent advice and, OP, you may or may not understand that it's actually more about psychology.
Higher rates help filter out demanding clients and also make it "worth it" when you do get a demanding one. Higher rates helps focus you, with 20 cheap clients you'll feel like going bonkers. With one or two high-paying clients you'll feel focused.
With higher rates and therefore more focus you also provide better customer service during the day. That will help reduce the amount of off-hour communications (this is also a boundary thing that Patrick already mentioned, be firm). Clients that understand that they get what they pay for and are comfortable paying a higher rate usually let you do what they are paying you to do and only communicate on the set meetings over minutiae.
My rate for each of my team members is 200+ per hour depending on what package they purchase (more hours = slightly lower rate, less hours, higher rate). We target corporate clients. Just it's been going so fast and been so stressful, it's not about the money. We've gone from 2 founders to 10+ employees very quickly.
And keep in mind, you'll want to be giving your employees a pay raise as well. They'll know what the clients are paying. Not a 1-to-1 increase, but maybe 30%. Make sure they realize you value their work.
$300 isn't unreasonable, there is a small dev shop in town with a proprietary CMS that charges $315 for creative/development work; and they're one of the most successful around town.
Higher rates help filter out demanding clients and also make it "worth it" when you do get a demanding one. Higher rates helps focus you, with 20 cheap clients you'll feel like going bonkers. With one or two high-paying clients you'll feel focused.
With higher rates and therefore more focus you also provide better customer service during the day. That will help reduce the amount of off-hour communications (this is also a boundary thing that Patrick already mentioned, be firm). Clients that understand that they get what they pay for and are comfortable paying a higher rate usually let you do what they are paying you to do and only communicate on the set meetings over minutiae.