About vacation, I have a few tips.

I live in Europe, so the context for these is when visiting another European city for 3-7 days, with the intention of getting to know the city and local culture better.

How to get to the place varies a lot, and there's no tip here other than the usual: ride shares (blablacar.com) and scouting for cheap flights/busses/trains.

1. Accommodation

Usually, the most expensive part of these trips is accommodation, and it'll of course vary a lot based on your tolerance for crappy rooms.
I'm older and won't do shared bedrooms anymore, so my tip here is to use booking.com or airbnb to find a room as far away from the city center as possible, as the price difference is huge. Just make 100% sure that there's public transportation from that place to downtown and that it's not like a 2h commute.

2. Food

Do not, ever, eat at the tourist places. It's always expensive subpar food. If you want to experience a city's local cousine, eat where the workers go out for lunch. You can find these places in google maps by looking at the photos: local places are usually shabbier looking and the reviews are in the local language. And of course the prices.

3. Activities/attractions

Cities often charge for going into museums, historical buildings, etc. These can get pretty expensive depending on how many you visit, so make sure to look for weekly passes, you can save so much money with those.

Also, and some people think they're lame, I've only had extremely positive experiences with guided city walks/bike rides. They're usually extremely cheap (5-10 euros total) and you learn and experience so much in one go.

4. Transportation

Do not take cabs around, that's throwing money in the bin. Look for a daily/weekly public transportation ticket as soon as you get there, and you'll experience the city in a slower and more genuine way.
Rental bikes can be a great option too.