Lex basically covered everything I could say, but I do want to expand on a few things.
Scope is important. Knowing your limits is important. Is it your first project? Don't set yourself an over ambitious goal such as "I'm going to include the 7 Regions + Gensokyo and my own fan region". First and foremost, that's impossible, as RPG Maker XP only has 999 available map slots, and even if you cram all interiors for a city/town into one map for that city/town, you're left using aprox 100 maps a region, that doesn't even include Dungeons and exteriors and other unaccounted for maps. Secondly, it's too much work. As you noticed in World Link, Java was literally a region of Lv.100s with no real challenge to it, just Numbers(TM). You'd hit cap by the second region, guaranteed, then you have to work with Level 100s for another 6 regions, and that's just no fun. There's so many things here from experience.
In a nutshell, don't make the game too long. It's a death certificate you sign for your project, and makes you weary. For a project, start small. Plan one region - or, hell, plan a sub-region. Make the game have a concrete beginning and ending. Know what you want, don't go planning things that are outside your skill set. Basically, look at Faith & Prayer Version, take a good hard look at it, and think - what are the flaws this game has (Because it absolutely has flaws). That link that Lex posted is a good place to look at feedback from someone who has probably never made a game before, and thus has no idea how hard it is completely rails on a game.
But above all, like lex said, have fun working on it. If at any point is stops being fun for an extended period of time, ask yourself - "Is the final result really worth slogging through all this tedium?" Primarily, you should make it for yourself, not for anyone else (Unless it's like, a present or something). Make the kind of game you would enjoy, one that appeals to you. The opinions of others can help shape the game, and provide feedback as to the game's direction, but what's the point in making something you won't enjoy and aren't enjoying?