First you need to define "low magic", because that could mean almost anything. I'm also intentionally avoiding the "official" definition of low/high fantasy because it isn't useful for this conversation. You also specified "low magic" instead of "low fantasy" which means you could have a fantasy setting with a ton of weird wacky races and landscapes as well as strange materials, but low magic- we don't know.
Second, you should also specify "low power" or "high power", because you can have low or high power magic in a low fantasy setting. For example, Lovecraft could be thought of as having "low magic" but magic can do crazy shit, like summon Gods, so make sure to be specific.
However in brief->Low Magic will usually be based on either subtle manipulations of Fate (think curses that end up coming true through circumstance or lucky talismans etc) Or be based on a magic-as-science>This magic will usually be based less on mana/magical energy and instead on things in the world. Alchemy, Rune-Crafting, Summoning Demons or similar is about as direct magic you can get. Very few if any spells or magical blasts>Magic is usually tied therefore to a skill and its rarity is attributed solely to either a bad reputation or it being a secret art only taught from master to apprentice