Leaves of three
You could start by comparing it to photos of poison ivy from a reputable source. It's also helpful to read the text which describes in more detail what to watch for, for example, the hairy growth of the tree trunk & the berries which you may or may not see, and also tips for recognizing in the "off-season" when the leaves look yellower and/or fall off the stem. The source below is a good one:
Two things that are commonly confused with poison ivy are:
1. Boxelder seedlings and
2. Virginia creeper.
This article below includes both photos of those lookalikes and also text that describes what to look for.
Good luck and be careful,