Honestly, what is there not to really like at a dollar tree, besides the quality of a few items? If you know how much everything costs outside of this store, and know how to save and spend money--you're on the right track.
I often come to this place if I need cheap, extra items for an event/to decorate an event or for arts and crafts stuff. My general rules for all dollar stores are:
(1) Don't just grab. Dollars add up at the cash register.
(2) Know what you're buying. Check the quality of your items.
(3) Compare prices.
Be smart and have fun saving :)