Hiya, I'm wanting to start working on rsps's and am not sure where to start. I have coding skills, just not much knowledge about how rsps development works and what is needed. 

I'd appreciate if someone could help me out, my discord is hellabeatz#0202

Willing to pay for your time

I think it's important to first think about what revision you like. osrs, rs3, rs2? If you've made that decision you can go to the download section and select a base you would like to work on, a small note every project will have its downfalls. Nothing is bug proof or complete. They al need work to become something special.

After that you can download Intelij and start the server (most of the items it's by running the launcher.java file). And the client (Loader.java file). When you've done that I would suggest exploring the server you picked, look a bit around, find things you can improve, maybe make a trello board for tracking your content.

Feel free to ask me specific questions if you need more info. 

Yup like SHNEK said take one source and start exploring it. Try to get basic knowledge of project structure. Simply try add dialogue to npc. you will learn where you handle NPC clicking, dialogue senders, writing dialogues. giving some output by Itemassistan or what ever you like.