You will want to transfer pollen from young (just recently opened) flowers to styles on older flowers. Aloe flowers are protandrous (male parts develop before female parts). When I observe bees at work on the flowers in the garden they go for the young flowers first to get pollen.
The general rule is that aloes are self-incompatible. There are plenty of exceptions. Generally aloes which make a lot of fruit every time they flower have a higher chance of being self fertile, in my experience. I do not have any experience with Gonialoes, though, so go ahead, try it and see what happens. It would be nice to find a list of aloes which are known to be self-fertile, or at least there are self-fertile clones in cultivation. A partial list here where this is indicated in the database (largely for the Lomatophyllum group):
https://garden.org/plants/grou...
