If your are new to the beta and real beginner as Toss - this might(!) help.
I love to go fast observers. So I go for Gate => Gas => Core => Robotics-Facility => Observer.
As soon I get the Core I update the warp gate tech. After Robotics I build an obs asap and scout the enemy. This might fail to very early rushes but I wrote this for pure beginners. I think you can do it =)
Against all races I tend to not early expand.
1)vs Terran:
I won most games with void rays. Of course build some stalker & one or two immortals.
Somethimes it comes to an 'elimination race'. Just build pylons and allthebasewillbelongtoyou ^^
I don't like it but it works.
If Zerg goes Hydra go for Collosus =)
Keep the obs around to check for Muta (counter with sentry).
2)vs Zerg:
Beginners like you will go Roaches. So go for 3 Immortals and some stalker. You have an obs from the start. Be cool and take it. You have to mix the amount of immortals and stalkers comparing to Zergs Lings and Roaches.
3) vs Protoss:
hm... I got lucky most times. They wanted to Void Ray me. So I did a timing attack with Stalker/Immortal. Obs ftw! Mirror matches still are strange *^^*/