where to buy an investment property

I have posted on here before but no one answered. I am looking at buying an investment property I can only afford around $250000 I am looking at an area called deception bay in qld as their is a train line going just about up to that area in Brisbane soon, I can also get a return of $300 per week. I am also looking at an area called armadale near Perth,have any realestate investors got any advice.

And Thankyou very much in advance.