Required Documents at the immigration office

In general,  immigration officer asks for your stay, address of your stay, sufficient balance (though many don’t  ask), return ticket.

Because you are visiting Singapore then you must have return ticket. You may change the return date at later stage when you are here.

Don't tell that coming here to search job. This is big NO. Your return ticket date should be reasonable like 1 week of your arrival.

To find a job in 30 days is very challenging and even if got a job your work pass approval can take a month or so. This is a very expensive place and secondly Airbnb option not available.  So, you need to stay either in hotel or executive apartments or any friend’s place. I think 30 days default visa one time entry you can get after then you have to leave Singapore.

During job search dont pay any money for a job here. its illegal in Singapore. Good luck

As Surya said, you will probably receive a 30 days visit visa on arrival.

They might ask for your return flight ticket, hotel booking (or address of a friend where you stay for free) and proof of sufficient finances - Singapore is expensive, so this should be S$100 per day or more, plus the hotel cost (or an international credit card).

If they suspect you are looking for a job, they might deny you entry (i.e. make you book the next available flight back home, of course at your cost). So think of another convincing purpose of your visit! (Hint: Tourism is not believable for a 30-days-visit in a place with few sights and an average visit duration of just four days.)

You will not find a job and get the required work visa for it within 30 days, so you will have to return home before the visit visa expires.