Another recommendation is the The BBC Radio 4 Broadcast of "Tracking The Lincolnshire Poacher", which also includes a short interview with the creator of The Conet Project:
1) When deleting a section, it would be nice if you placed the confirmation box closer to the delete button, instead of using the browser's built in confirmation dialogue.
I've gotten better at it with time and so will you. Learn from your past mistakes/misquotes.
I analyse each task involved in a project and estimate the hours per task. When in doubt I try to split up the tasks even further. When done I add 10-20%. For me, if the price feels a tiny bit too high it's usually fair for both me and the client.
If I get good ideas for extras I propose them to the client while or after delivering the initial project. Don't add it for free unless you can afford it.
https://www.youtube.com/watch?v=Wvr6o7fBcTY