Your question has no single answer. "Get" is a flexible word that means too many things to count. You can almost think of it as a wild card that means whatever it needs to mean in a given context in order to make a sentence make sense. Without knowing the context in which your sentences are spoken, one can only guess what it means. For example, "let's get you to start" could indeed mean "I will help you to start". It could also mean "let's make you start". Or, it could mean "I choose you be the one (out of a group of many) who starts". Or, if your car isn't working, it could mean "let's fix your car so it will start". (That might sound weird since it is the car, not you, that needs to start. But people will talk that way sometimes. For example, a mechanic might say "I will have you up and running in two hours."). There are hundreds of possibilities. In sum, don't worry too much about the meaning of "get" and use it as little as necessary. If you avoid it, your English vocabulary will expand.

Yes, "Let's get you" generally implies helping, guiding, or encouraging someone to do something. Here’s how it works in your examples: 1. "Let's get you to bed"
This means "I'll help you go to bed" or "I'll ensure you go to bed." It suggests assistance, encouragement, or taking steps to make sure the person goes to bed. 2. "Let's get you to start"
This means "I'll help you start" or "I'll encourage/motivate you to begin." It suggests initiating an action or supporting someone in starting something. So yes, the phrase often carries the meaning of helping, ensuring, or motivating someone to do something.