Start with context, not a test
The most common opening message is some version of “what can you do”. It is the weakest possible start. Companions respond to detail, so a sentence about your actual day gives a character something to work with and immediately sets the tone.
Pick the companion, then the topic
Each character on slowshop is written for a different kind of exchange. A study session with a companion built for late-night storytelling will feel oddly theatrical, and a slow reflective evening with a character written for momentum will feel rushed. Read the character page first.
Let a story accumulate
Collaborative fiction improves with repetition. Give a place a name, give a character a habit, and refer back to both. Continuity is what turns a series of scenes into something that feels like a world.
Say when the register is wrong
If a companion is being too cheerful, too formal or too fast, say so plainly. Characters adjust to direct instruction far better than to hints, and the correction usually holds for the rest of the conversation.
Keep the personal details out
Conversation works perfectly well without addresses, account details or anything else you would not type into a public form. Treat the exchange as you would any website and keep sensitive information to yourself.
Know when to stop
Company is useful, and it is also finite. If a conversation is standing in for something you actually need from a person or a professional, the honest move is to close the tab and make that call instead.