Define your travel angle and reader
A general travel newsletter competes with every travel media brand. The ones that build loyal paid audiences own a corner: budget travel in Southeast Asia, slow travel for remote workers, luxury travel under $300/night, city guides for business travellers, solo female travel, van life and overlanding. Pick the angle that matches your genuine experience and the reader you want to serve. "For people who travel like I do" is a better brief than "for people who like travel."