Physical products like books, clothing and merchandise are final once they go out the door. So it’s important to get things perfectly right. Once shipped, it’s very expensive to fix any flaws.
A website, like any digital product, can change almost immediately after launch. Nothing is ever final on the web. This is a huge benefit. It means you can quickly launch, test and iterate. For example, say you want to add a donation form to your website but you are not sure what form fields you need to collect. Add the fields you think are neccesary, launch it and start promoting. Give the form a couple of weeks to collect some real results.
Now look at those results, see where donors drop off. Are they filling out their name, email but leave when asked for a phone number? Try removing that field and running a new promotion. After another two weeks compare the results. Is it better? is it worse? If it’s better, leave it as is. If it’s worse then do some more research, ask some friends and colleagues what would stop them from donating. Adjust accordingly and try it again.
A great web experience is built over time by trying things that you think might work, getting feedback from users, making changes based of that feedback and testing it out again. Repeat that cycle and eventually, you will create something remarkable that helps the people you serve.