I grew up with a very generous family, so I have to say I don't understand some of the evangelical "cheapness" that goes on. And by this I mean, taking joy in not spending money -- especially when perhaps you should. Case in point, if you have the money to clothe your kid, but allow them to wear castoffs that don't fit -- it doesn't send a message to unbelievers that, "WOW! They are living for Jesus." Or, "That family cares about the heart, not appearances! Good for them." It sort of says, they gave their kid a snake instead of a fish.
We all have a spirit of poverty somewhere in our lives -- maybe it isn't money. I know both rich and poor people with a spirit of poverty and that is, by my definition, taking care of yourself and your needs first, not trusting God to do so.
Attitude is a biggie here. Non-financial example: If someone else has a bestselling book, instead of seeing that God has designated that book and that author for that time, a person with a spirit of poverty says,"SHE TOOK MY BESTSELLER STATUS!" As though God made some kind of mistake.
When I first became a Christian for myself, I hated to go out to dinner with any Christian group, because inevitably someone wouldn't leave enough tip and I knew, I'd be shelling out more money to make sure our witness wasn't ruined. I grew up in a Union family, I appreciate a skill and I consider a good wait staff SKILLED and they deserve a day's wages. If I couldn't afford to leave a tip, I'd go somewhere cheaper or wouldn't go! But I've seen good Christians take the stance that the restaurant charged too much and they weren't expecting to pay that, so they got enough. Regardless of what the bill read.
Consider others more important than yourself. Money is nothing to God, absolutely nothing. When I put out money I don't have for a worthy cause, HE always, ALWAYS replaces it for what I need. It's the one verse in the Bible where He even says, "Test me in this." (Malachi 3:10)
Oh and then there's the judgment when someone HAS money that they're not spending it in a Christian way! "Did you see her car? Did you see her house? They're not Christian." We have no idea what's in people's hearts or why they do things, or what they give in secret! But we also don't have a right to judge -- just keep in mind, do you have a spirit of poverty somewhere? (Which comes out of fear and greed.)
Mine is hoarding. I had a mentally disabled brother who stole everything in the fridge at night, so I hoard things. Including: $60 Christian Dior spray-on makeup because once I went and they were out of my color. And I have a fear that I won't get what I need and Lord forbid, I might end up in drugstore makeup! I also hoard Mr. Clean sponges and laundry detergent/fabric softener -- like all heck will break loose if I don't have those things at the ready.