Cut your planning in halve as that's what you'll actually be able to do.
Playtest as often as you can with friends and others as you'll never realize how unintuitive your choices are until you see someone else completely miss it.
Try to make a game design document. It's a tool that can be incredibly usefull, doesn't have to be longer than a page, and basically tells you exactly how to make your game concept.
Have fun!!!
Probably plenty more tips to give but these ones came to mind.