I do all my quotes etc on paper. Then type it up on Workflowmax. You can then turn it to a job. Allocate time and materials to the job. Then invoice at the end.
Then it will give you a nice pdf of how much profit you made.
Joist App is free, also has Apple/Android apps that syncs. Pretty cool for a free tool. Failing that, there's Powered Now too, think that's about a fiver a month.