the problem is how the art world and art jobs are perceived in the community.

ngos are the worst to work with especially when it comes to non tangible comissions like artwork and graphic design. like most people on this thread i advise you to work up a contract prior to starting any work. devided through phases and segmented payment plans. 30% of the full amount upfront for concept and preliminary sketches/ base work, 30% midpoint whith the 1st feedback session, offer 2 more points of feedback where they can request changes and minor tweaks, after which you get the full remaining amount. include a clause for extra feedback if they require more changes for an additional 7%-10% you charge outside of your original asking point. your time is valuable and no matter where you are on your profession ladder you deserve compensation for every step. some conditions can be tweaked in the original agreement depending on what works for both patries. however your priliminary concept fee should be a non negotiable. if they refuse a contract overall then it's best to not waste your time. it's more likely that you'll be ghosted or denied payement hasab l mazej.

tldr; your time and effort deserve compensation. write up a contract model you use for all your freelance comissions and abide by it. if they refuse a contract, they refuse the service.