I've done a few direct sales jobs - Avon, Ann Summers and Usborne have been at various points in my life, but i wont say which I do now in case I get accused of recruiting.
They get a bit of a bad press, but I can only think they are from people who couldn't be bothered - all three had me earning at least double minimum wage within three months, and it went up from there. Not Xenia level, but not bad considering every other job has been minimum wage and stupid hours, if the job is even there.
My main tips for direct sales:
Research before you join. Not just the company, but who you join with. Most of these companies have a pyramid structure, so whoever you join with has a vested interest in you earning and staying happy. Never just join through head office. I would say that the best option is someone with a smallish team, who is ambitious, and who has someone very successful above them. That way you get the expertise of the successful person and the personal help from the ambitious person.
Choose something that will work in your area. Avon does well in areas with lots of low paid people in a good community. Ann summers is brilliant with students. Usborne for the middle class pushy mums. Lots of competition isn't always a bad thing - awareness of your product will be high.
Grab every bit of extra income - raffles at home parties, special offers from one catalogue sold a full price from the other, etc. keep thinking of new ways of selling your product - do stalls, Facebook, internet. Get n touch with groups and clubs who might be interested in either buying (end of term presents?) or letting you hold a stall.
Recruit. There is only so much you can sell, but recruits keep bringing in money. Support them well and they will become friends, too.
Be positive - your first few weeks may not be very lucrative. Carry on.