So you look at the RMVX RTP and decide "Hmmm, the type of character I want isn't there. Lemme go look for a new one!" or that you want your game to actually have its own look. This is great! Be careful of where you take your resources from though.
If you make them yourself (and you indeed can do this, and for a shameless plug, my own pixel blog at http://pixel.oceansdream.net
goes over some of this!), then that is no problem. But if you're looking for resources available online, take a bit of care first.
When looking for resources, be sure that the resources are actually available for use. Just because you see a graphic online doesn't mean it's ripe for the taking. Some people may not want to see their graphics in anyone elses game, and some people are just fine with it as long as you give credit. Please do. Write it down somewhere even, so you don't forget later to credit them!
If you see a graphic and are not sure where it's from, ASK. There's likely someone who will know. Then it can be found if it is okay to use it or not. Some people make resources gladly for other people to use. Some people don't want that. And doing something like ripping graphics from another indie game is terrible. Even if the game is in a different language, don't assume you can just get away with it. Use resources that are available to use, try making your own, maybe ask or pay someone to make you some, but don't rip other peoples resources without permission!
If you try to contact someone about if it's okay to use a resource and they don't get back to you, assume it's NOT okay to use it unless you're told otherwise. They might have switched emails, rarely check it, or some other reason but might still not want to see their graphics used.