My hubby and I are on roughly $650 per week, with me not working...
I do a budget every few months for the next 4 months in an excel spreadsheet, with the dates, what expenses there will be and when pays come in with a running balance. That way you can plan ahead and then check to make sure you haven't spent more than you should have.
I go shopping on days other than Thursday and Friday (when most shoppers shop), so you find more things reduced - like meat which is expensive for the amount you get.
I buy 2 or 3 boxes of nappies when on special (around $30 ea).
If we get take-away, I make sure it's somewhere that has a special deal, like red-rooster mon-wed 1/2 price chicken and chips, pizza hut vouchers for $3.95 pizzas, etc.
We have telstra mobiles, which have a 'my hour' when calls are free for the first 20 minutes of the call. We try to use this when we have long distance calls or need to give someone a quick ring - just make sure you don't go over the 20 minutes. Hang up and ring back again!
My hubby and I have $80 per fornight to spend on whatever we want (my $40 goes on the gym membership, and sometimes I use his too wink ) which is a way of not feeling deprived, and me getting into shape.
We put between $400 and $800 per month into an award saver account (depends on what expenses there are that month), and use this for any out of the ordinary expenses - new clothes, new baby things, holidays, etc. We try not to touch it very often as it only gets interest if there are no withdrawals in the month, so when we do withdraw, we make sure we've planned ahead that we won't need to again for a while. We have it more as a separate account that doesn't get used, but the interest (if any) is a bonus.
When we got married we were both still at Uni, and living only on Youth Allowance and what Hubby got from a casual job (although we didn't have a baby then) - it can be done, it's just a matter of finding a way for it to work!
All the best,