Escargo Express is your friend, use it! There's so little inventory room when you begin and even towards the end of the game when you have a lot of items. Using Escargo Express to take away some of your unneeded items reaaallly helps clear your item space for more items that you actually need. And that way you aren't getting rid of items you don't need at the moment but might need later.
Also sound advice! This is ESPECIALLY handy when you get Jeff on your team. If he fixes a broken thing and turns it into a weapon for himself, after you upgrade FROM that weapon, you're stuck with his old weapon because you literally can't sell it if he made it/fixed it himself. Escargo is a
godsend in these cases. It's also handy for putting away items you only need at certain times (Pencil Eraser, for instance).
And while I'm thinking of it, another great thing to do for level-grinding/experience building is to beat a boss of an area and THEN grind afterward. The enemies will be running away from you if you beat the boss (like Sanctuary boss locations, for instance) and it makes for some really easy experience when you get surprise attacks on those enemies. Going one by one can sometimes get you insta-wins, too! Another thing that's handy to have with you if you're going into a somewhat lengthy dungeon, is an Exit Mouse. If you need to get out in a hurry to sleep/recover, they'll take you right to the exit. It can be a big help when you get to the Gold Digging site later in the game. (That place is murder.)
Also, if you see an enemy/group of enemies you don't like, sometimes just walking off-screen a bit can make them go away/spawn into something else. This doesn't ALWAYS work, but sometimes it does.
With Jeff, it's also really handle to stock him up with bottle rockets/big bottle rockets. They can do MASSIVE damage to one enemy and sometimes one or two-hit bosses at times, too. And they're generally not too expensive!
And I don't know if you're to Twoson yet, but don't waste your money on Orange Kid. He's useless. : (
There was one more tip I had for you, but I completely forgot what it was... I'll post again later if I remember it.
This:
http://www.ebay.com/itm/Earthbound-...712?pt=LH_DefaultDomain_0&hash=item3cf2c9f1f8
After posting I noticed the official Nintendo seal was fake. So I am thinking its a homebrew.
Ohhhh, okay. Yeah, that sounds like a scam, to be honest.