I have been working on different kind of software projects implementation using the water fall methodology. now some of my clients want to shift to agile methodology. what do I need to take into consideration for such a change and what steps needed to start follow up with the new methodology though some client will remain working with using the waterfall way but some clients are insisting on the agile way.
A good way to think of the shift from waterfall to agile is:
Waterfall: We plan as much in advance as possible and do the work following that plan
Agile: We anticipate change happening and as a result we want to either have flexibility in our plans or we want to keep our plans short (iterations)
When your customer asks for agile delivery they mean they want to see an incremental delivery that allows them to give feedback as the work is being done.
Agile and waterfall are not methodologies. Waterfall is a kind of project lifecycle whereas agile refers to a more general approach to organization and productivity using techniques which emphasize practices like iterative, incremental and continuous delivery, self-organizing teams, customer collaboration and responding to change.
I suggest you could start by reviewing some of the practices associated with Scrum and Kanban - two of the most popular frameworks associated with agile ways of working. https://www.agilealliance.org/agile101/
For software development frequent delivery is key. Aim to deliver working software every week or even every day, allow people to use or review it and then use their feedback to improve future iterations of the product.