Which area Will Suit me Best.. Im a guy, 25 years, Will live alone, in centrum, close to shopping, bars and restaurants
I'll put it simply: most of Centrum isn't nice place to live. It's noisy, many of the old tenements are full of drunks, etc., the only nice neighbourhood in Centrum I can think of is the area near Zamek, it's safe and quiet most of the time.
If you really have to live in Centrum try some new apartment block; the idea is that you want something built after 2000.
You don't want to live in any right bank neighbourhood because you'll spend a lot of time commuting.
You don't want to live in any northern neighbourhood (Gocław, Golęcino, Stołczyn, Skolwin) as they are the bad neighbourhoods with crap public transport.
Niebuszewo has great access to public transport and facilities but is infamous for being bad neighbourhood (I think it's infamy is overblown, but...)
Pomorzany has great public transport but most of it is grim commie block concrete jungle.
So if I were you I would look for apartment in Pogodno or Gumieńce. Both are quiet, safe, have many green areas and have good public transport to Centrum (15-20 min. tram ride). Especially Pogodno is nice.
Other nice neighbourhoods are Warszewo, Krzekowo, Bezrzecze, Głębokie and Osów, but they are more remote.
Which sites are good for finding apartments for rent? I have used everbest so far are there any Else?
Try otodom.pl. Basic real property Polish: mieszkanie = apartment, dom = house, na sprzedaż = for sale, na wynajem = for rent.