When someone asks how long it takes or the likelihood of ranking higher?

How exactly do people word this in a reply when someone asks the guarantee something will rank higher or how long it takes, what's your responses?

Honestly speaking you need to work around various elements however, Backlinks and Fresh content (optimized for search engines) works fine in most cases. Here, keep in mind that the quality of your host is going to play a vital role too

Simple, you tell them that like in all business, nothing is guaranteed and there are always risks involved. Google could completely change their algorithm by tomorrow, but judging from past your experiences and client success, you're very confident you'll be able to get them tangible results within 60-90 days of starting the project.