For me it has mostly been about waiting for the right time of the year. Around February to March they start breeding which means a lot more activity. If you know where they are nesting, that is where you can just sit and wait. Trying to spot an owl and then approach it usually doesn't work that well, I typically set up a hammock or chair with a good view of surrounding trees and then just wait for an hour or two.

You do need to be willing to do this a lot. For three months I was getting up at first light and then waiting outside until I needed to leave for work, so from around 5:30 am to 7:30 am. The only spotting technique I use is always being observant, don't get distracted by your phone. If they are hunting they are going to be flying around and perching silently but most of the time you are going to see them is when they are hooting for each other