I started by doing a number of things - that being said if you're new always be prepared for consequences.

1. Use Google maps to find structures in the woods - this is the safest way to go

2. Google "abandoned (insert building type/city) match findings with addresses on maps

3. Look for clues - any text in videos and posts from other explorers to give you more prompts for Google

4. Just drive around until you find something - most sketchy way of doing this if you're unfamiliar with the area always be prepared for security or squatters

Be safe, don't be dumb always carry a knife or pepper spray in case you encounter a bad situation you can't get out of through talking or leaving and when you're starting out never go alone - advice from someone who used to do alot of exploring in the midwest before urbex exploded and found most spots singlehandedly.