How do I get a higher prestiege?
The prestige number (shown on the up-left corner) is a number from 1-5. Every decorative object gives you 0.00x of prestige, every guest the same. For example, a hotel certificate gives you 0.02 of prestige, what means that with 50 hotel certificates you will have 2 of prestige (or "stars").
That means that you don't need, for now, any minimum things (days played, guests...), you'll get prestige by the both ways (if, let's say, 100 happy guests, it would increase on 1 the prestige level, or 50 guests and 25 hotel certifcates).
But you can loose prestige too (guests leaving before they should and selling the decoratives objects).
To get prestige you need guests leaving happy (by "happy" I mean that leaving at the time they should: even if they are angry, if they pay the full room price it will increase a bit the prestige) or to build decorative objects (everything that hasn't got an utility are decorative objects, for example: paperbin and bin, lights, pictures, sofas... The "Hotel Certificate" object is the expensive but is the object that more prestige adds).
That is how AvrGames explained it in Hotel Tycoon Alpha 4 post.