First time selling IP - avoiding "second Chance"

First time we are selling one of our IP's. It is located in Kalgoorlie-Boulder WA and and the lower end of the market.
Suitable for first homeowner, but as there as lots of new people in town want to avoid signing the contract and then finding 3 weeks later prospective buyer can't get finance. How can we avoid signing or would it be fair to just put the house on "Hold" for 48hrs to get a conditional loan approval letter.

Second market it to Investors would it be worthwhile paying for an ad upgrade on Is has been contingently rented for the last 7 years we owned it. Thanks for any post and advise
Two ways to be more sure about finance:

1. Do not accept a contract with a finance clause
2. Ask for a higher deposit (i.e 20%).

Yes, pay for a premium ad if you want to get more exposure.
Asking price $227,000. "Currently rented at $335 per week until August 2013 (with the option of earlier vacant possession if requested), this property offers investors a tidy 8% return on listing price."

As an investor I can get better returns in outer suburbs of Sydney.

BTW the gross yield is 335*52/227,000 = 7.7%. That's untidy rounding. :(
Oops, better get the yield changed ..oh the realestate agent knows it is rented under market value (should be $360, but can't change this until August) and it is unlikely that an investor will pay full asking price but still should not be advertised like this.Will get her to change it. Thanks for the advise about the deposit, but in WA there is not often a deposit paid.