Pine work is calendar dependent. Since you are in the southern hemisphere it may need a bit of translation too.
Usually the first step is getting the tree very healthy. This is usually evidenced by strong candles. Since it's winter is just ending where you are, we wouldn't expect much in the way of candle growth at this point.
The following holds for all types of pines:
1) Assuming its in reasonable health, you can begin by removing needles that are growing within one inch or so of all the branch junctures (where there are Y formations) New twigs form from dormant buds within the needles, and the points at which you already have branch junctures are not points where you need more.
2) Next step is judicious thinning of mature needles. You want to leave more needles on the lower and interior branches. This depends on the variety of pine. If it's a black pine in very good health, you might leave 8 pairs of needles on the upper and exterior branches and more - like 12 or more on the lower ones (assuming they have that many!) The needles to be left should be those at the extreme end of the shoot.
If the plant, or specific branches are weak, don't do anything with those. Be very cautious not to bend or break needles on other branches and it's a good idea to hold the branch in one hand while you pluck the needles with the other. Many people advocate the use of tweezers for needle plucking, and bud selection, and you can find some of those on the TreeBay site.
If it's a corkbark tree, red pine, or white pine, they aren't as vigorous, so you don't pluck as much. Corkbark is also brittle, so be careful!
Moving into spring it's time for bud selection. As the spring buds form you will probably count more than two buds on the strongest shoots. You might see 4 or even six or more buds forming. You can reduce those to just 2, and pick the WEAKEST. On the lower and interior branches you may leave 3, but pick the STRONGEST.
In late spring the shoots will begin to extend. Depending on the method you are using, you may be pinching back long candles, or you may be allowing them to grow out to be removed entirely in the late summer. The second method is the one I advocate in the
TreeBay Bonsai Tools & Supplies article, and you can read more there. New buds may be removed with the tweezer or sometiimes rubbed off in a downward direction if they are still small. When they are larger they need to be cut.
For white pines, we generally pinch back 1/2 of the weaker candle and 2/3 of the stronger before the buds start to show white in their sheaths.
I hope I haven't confused you by trying to make this a general treatment. If you have more questions after you've begun the process of cleaning out the branch junctions and plucking some of the needles, just post a picture and we will pick up from there. Ideally the plucking is a fall (I almost typed "October," slap my hand), but you can cheat it a bit to get your tree back on schedule.
Regards,
Matt