We make the work terms and agreement as per the interest of the clients but we usually prefer the following milestones based structure:
30% before the start of the project
30% on completion of Milestone-1
30% on completion of Milestone-2
10% after the project is delivered.
For smaller projects, we charge 50% upfront and 50% post project completion.
We also provide three months of free support and maintenance. Just ask for it!