Different people have different pollination techniques. My technique is based partially on a technique described in a great article by Steven Hammer (25 ways to look at Haworthia. CSSA journal 70(4) 171-176) partially on conversations with other haworthia growers like Mary Parisi and partially on my work experience crossing Arabidopsis.

Look up pictures of stigmas and anthers to familiarize yourself with the flowers sexual reproduction organs. The goal is to rub pollen from the anthers onto receptive stigmas. As soon as the flowers open the pollen is usually ready, but the stigma, the female part of the plant is not receptive to pollen yet. The stigmas become receptive a few days later. So use pollen from newly opened flowers to pollinate the stigmas of older flowers. You can tell when the stigmas are receptive because they expand a bit.

I use very fine tweezers to pollinate. In between pollinations I spray the tweezers with alcohol to prevent unwanted contamination. When I first started hybridizing Haworthia I could clearly see the anthers and stigmas and pollen. But now almost 20 years later reading glasses are essential.

When pollinating first define the male and female parents. As soon as the flower of the female parent opens use the tweezers to carefully remove the three lower petals. Then carefully emasculate (remove the anthers) from the flowers being careful not to damage the stigma. In the next couple of days watch the stigma. It will elongate and swell slightly. 1 or 2 days after emasculation start pollinating the stigma. For the male parent use flowers that have just opened. Remove the lower three petals and examine the anthers. Most of them should be covered with pollen. If not use a different flower or wait a day. Use the tweezers the remove a filament stem with the anther attached. Gently rub (if you do this too hard the stigma will be damaged) the anther on the stigma until you see that some pollen has been transferred. Do this for two or three days in a row. It takes some practice. The best time to pollinate is in the late afternoon. There is variability in how much pollen is shed and this can affect pollination outcomes. You will know that the cross was successful by the formation of a seedpod. When the seeds are ready the top of the seedpod will start to open and you can harvest the entire pod. You can cross almost any haworthia species although more distant crosses are more difficult.