well as a professional from the book (Clean coder) Robert C Martin. You should know how long it will take you to implement features. What you say is what they a

well as a professional from the book (Clean coder) Robert C Martin. You should know how long it will take you to implement features. What you say is what they are going to agree on. if that's the case, don't make any unnecessary gambles. only work on and with things/components/libraries you know and have worked on before. When it comes to scope creep it changes the project and if anything changes the project, any new deadlines must be agreed on/communicated before any changes are implemented. Be confident in what you can and cannot do. And always be professional about everything you sign. You can still have incremental reviews on how the project is proceeding and if they want to change or find out what they asked for is not what they want anymore just communicate the time it will take to implement the change and test it out.