Where to begin when searching for off caMpus housing

Have never had to go hunting for housing before and want to be fully prepared as a rising sophomore
How feasible is it to meet all these requirements:
- $1500 or less
- 1 bed or studio
- walking distance to campus

When is the best time to sign a 12 month lease for the 26-27 school year if I want to live alone?
What are the best resources to look for places (nu off campus site, Zillow, apartments.com?)