would it be a bad idea to make a D-hero Deck and add in Neo spacians?
if not any suggestions?

That is by far, the worst decision you could ever make in the game of yugioh. Stick with one, and only one, of those themes. E-Hero's, and D-Hero's, Can be mixed to a certain extent. What mixing two themes of those does is limit your options in the support area. There is plenty of support for each of those decktypes, and mixing them just limits you. So, Try a deck with both of them, and find your favorite. D-Hero's, are very technical, and E-Hero's are fairly straightforward, and a little faster. Build around some main cards you want in the deck, and go from there. Neo-Spacians in my opinion can be built to a competitive level, but it will take practice. One of the top decks in the world right now is an elemental hero deck called Big City. Good luck, and Happy Dueling. And, Welcome to Realms.

Things can never get done if you don't try them. Even if people think it is a bad decision always try first because it can't hurt you. Keep in mind different types of strategies and try to settle on one that you think is best and try it. No matter how bad it sounds you can always try it. Try the deck out first and if it doesn't work then you can try again or move on. Don't let people dicourage you just because they say it can't be done.

yeah in order to make my D-hero Deck..i'll need it...and thanks for the welcome ^_^

Yes, very. Stick to one theme.

Only Neospacian I would personally put into D-hero decks might be Grand Mole.

i agree with Aromis but i'd also play test a Dark Panther, because of his effect......