You don’t have to take the first property you see. The best way to understand what represents a good deal is to look at a lot of properties. Try and get as many as possible of your prospective housemates to come along to each viewing with you.
Bring a notebook with you and take pictures. That way you can list any repairs required – or any furniture you need – as part of your written offer.
You don’t have to offer the asking price. You could always offer a bit less.
Sometimes the landlord will accept a lower offer to get a good tenant.