My first box of tree decorations was a multipack of plastic baubles in three shades of red, bought the week before Christmas because I'd forgotten trees need, well, decorating. They looked fine from across the room and like a dollar store sneezed on the tree from anywhere closer. The lesson stuck: cheap plastic reads as cheap plastic no matter how many you buy, so it's worth being choosy about where the money goes even on a tight budget.
This is the kind of thing that changes a room more than almost anything else you'll buy this time of year, and it works in almost any home, rented or owned, tiny apartment or a house with a staircase to wind garland around. A mixed box of glass and matte ornaments in two or three colors makes a real tree or a fake one look pulled together instead of random, and it's the easiest way to make a first apartment feel like you actually planned for the season instead of panic shopping on December 20th. Traditional glass ones do heavier, older style trees well, the kind with big branches and some gaps to show them off. Lighter capiz or wood ornaments suit a thinner, more modern tree where you don't want everything crowded onto one branch.
Where it falls short is anywhere breakage is a real risk. Glass ornaments and a cat who treats the tree as a climbing structure do not mix, I learned this the hard way with a shattered one under the tree skirt two years running. Households with toddlers or a big dog with an enthusiastic tail should lean toward shatterproof plastic or fabric ornaments lower down and save the glass for branches above waist height. And if storage space is the real limiting factor, a huge haul of oversized ornaments is going to be a pain every January when you're trying to wedge the bin back onto a closet shelf.
Good glass ornaments age well if you're careful with them, the color doesn't fade and the silvering inside doesn't wear out the way cheap paint on plastic ones does after three or four seasons. Store them in a proper divided box, not a grocery bag, and wrap anything with glitter in tissue so it doesn't shed all over everything else by next Christmas. Fabric and wood ornaments are the most forgiving long term, they survive a move, a rough-handling toddler, and a basement that gets a little damp better than anything made of glass ever will.
This suits a home that wants its tree to look intentional without a decorator's budget behind it, real tree or fake, first apartment or forever house.