I think the best way to shop for most products on wollies online is to go by product type sorted by "unit price low to high". The "search by list" feature makes it a bit easier to find items of a specific brand or type, or help narrow down product lists so you're comparing apples with apples.
But there are a couple of things to note:
1) The unit price is the advertised price. Sometimes when a product is on special, the special unit price is displayed separate to the advertised unit price. Best to check for any everyday reward specials, baby club or multi-buy specials on the whole page first to see if they are better value.
2) Sometimes there is no unit price indicated. These are usually all placed at the top of the list, even though they may not actually be the lowest unit price.
3) Sometimes the unit price is on different scales, and $1 per 100g is displayed alongside $1 per 100mL and alongside $1 per 1EA! All of which are displayed higher in the list than $1 per 1kg.
4) When searching by product name, sometimes the product name is misspelled. For example, a search for "omo sensitive powder" doesn't give the best value item which is the 5kg pack, because the product name has a misspelled word ("powder" is "powde") and will only be returned in the search "omo sensitive powde".
5) The specials section is useful, but sometimes they will put a product on special but it still won't be better value than a larger box of the exact same product. I'm sure this marketing ploy is not specific to wollies online.
ok that's all I can think of. [Edit: title.]