@Faruk - First before you go to a freelance directory or hiring service consider this: the chances you get a full on plugin developer who actually knows all the ins and outs of WP in the giant pool of developers who check PHP + WORDPRESS + PLUGINS is rare. To clarify many developers in PHP may check the box for WordPress simply because they use it for their blog, this in no way means they would be an ideal candidate for plugin development as they may not even use WP for work/coding purposes.
My suggestion there would be to use these forums as well as the plugin repo itself to find plugins/authors that you already either have a connection with, already use and like their other products etc. This way you get a dev who already knows the process and can speed you through development.
Any PHP dev can pick up WP, but at what cost to you. For example if they are not already 100% familiar with add_(action/filter) and the 1000s of available hooks & filters, you just lost dozens of hours if not more already so they can look up everywhere they need to tap in.
Onto your questions:
How should I start?
Absolutely all of those, write down everything you can think of for your idea and organize it. Include mock designs of how screens should look, lists of potential settings with details of how they should change things if needed, and any functionality should be clearly mapped out in a 1 -> 2 -> 3 style process including underlying processes like saving data. IE Add to cart -> Checkout -> Save row to purchase table -> redirect to confirmation.
Lastly make a second list for your MVP (minimum viable product). Determine what items from your other list are most important to the core product. IE what can you not live without. Then create v1 with only those items in mind and get it out for feedback. Quickly follow up with the addition of your other features from the first list.
Working with developer;
Depends on the developer. Many work well with constant communication & feedback/testing, others want you to leave them alone. Establish which you prefer and make sure they are ok with that and stick to it early.
After finishing plugin;
- Do I need still a developer for bugs? 100% yes, WP changes, as do other plugins & themes you may need to stay compatible with. Even if you get 100% of your idea done in the first version (which you probably shouldn’t, see MVP above) you will need to keep up with those other changes you can’t account for.
- What should I do on updates from WP, a developer should update the plugin? See above
- Should I deal with developer hourly or project based? What do you offer? I personally don’t do spec work, and you may find lack of involvement over time that way. You may want to consider a partnership instead. Consider support, you may have to call on the dev to answer harder questions from time to time as well. Best to know they are always available when you need. A % partnership ensures that. You need a dev who can be there when stuff breaks to quickly get a patch out. If they are hourly or spec, likely you will have to reach out and schedule time to get a solution created. This could be costly. A partner dev is likely seeing the tickets before you are and has already pushed a patch before you had a chance to respond
And could you share a brief for the plugin development if you have?
Nice, nobody ever really leaves the floor open for you to talk about yourself haha. Keeping it short, reputation should speak for itself:
Popup Maker (freemium) - [repo] [website]
Ahoy (premium) - [website]
User Menus (free) - [repo]
Content Control (free) - [repo]
Easy Modal(free/retired freemium) - [repo]
Recipe Manager (freemium) - [repo] [website]
WP-JS-Form-Sample-Plugin - [github] I also write conceptual code like this sample plugin for admin forms which uses a JS based forms to render settings pages, metaboxes with minimal effort on the developers part.
If you opt to go the partnership route let me know. I have an extreme amount of effort/time put into boilerplate code which essentially jump starts any new project with instant functionality like settings pages, admin forms^ and more.
Otherwise hope this was helpful.