Install the editor and run it. I suggest you make a throwaway game first; make some objects like a treasure chest that gives you an item, a door that teleports you to another map, a couple of NPCs that talk to you, etc. Get a feel for all of the commands you can script.
If you're using RM2k, I suggest you plan out your items and how many you're going to need and in what order. In your inventory screen in the game, they're arrange as in the database, and it's a bother to rearrange them in the editor once you have an established game in development. This includes potions, weapons, armour, and key items.
There's a few things I remember from my own game. These are from RM2k, but I'm sure it'll transfer over.
- Use \n[0] to display the hero's name in text boxes. This makes it easy to change your hero's name and not have to change every textbox in the game. You can also use it for other stuff, like town names, by creating a dummy hero and naming it with the desired name (substitue the number '0' above with the hero's number)
- In general, the \x sequence in textboxes is pretty cool. Replace \x with various characters for various characters and effects (check the help file). If you're adept, you can alter them to display custom characters (I made one character for each type of item).
- If you're going to have special battle scripts/commands (scan, steal, etc), I recommend scripting them early on, so you can just copy and paste it into other battle groups. Try to do it before you create all of the monster groups.
- Think up game-wide things early in your development of your 'real' game. In my game, I wanted a running count of treasure chests found, but I had fifty-odd treasure chests already placed. I had to go and modify each chest to increment a counter, when I could have designed it in my template chest event in the first place.
- I had a small common event that made my character blink every thirty seconds or so. It was cute.
- F9 brings up switches and variable control panel during test play. I had a common event which activated off a switch to give me money, so I could properly test the game.
- If you can afford the time, I recommend you plan your game. Think up plots, draw out rough maps, etc. Though I found it fun to design-as-I-go, I really could've saved some time by thinking it out first.
- Understand your characters before you write their dialogue; in addition to whatever personality quirks you give them, remember that a deeper character wants something. If you can't find a motive for them to do the things you want them to do (like, a good motive), the characters will seem disconnected.
- I always carried with me a small notebook where I could write down inspiring things such as names, or work out statistics or item/monster placement
- When I finished my game, the latter part was much better than the first part. In the time it took to finish the game, I've matured a bit and gained a lot of experience with the engine. Look back and make changes.
- I had trouble finishing the game; I wanted to add this and this here, or tweak this thing here, or update a custom sprite there. Just one last playthrough for balance issues, etc.