Offer arrived, can I still ask for more? (update)

I received an offer as a marketing coordinator and I think the pay is a little low. This is my first time dealing with any of this. I have a competing interview next week. What wording worked?

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.

Most employers expect a short conversation. Mine did not even blink.