DIY insemination works best for lesbian couples who are using a friend or acquaintance as their sperm donor. For this method to succeed, it is essential to have access to sperm when you most need it during the ovulation of the partner who is intending to get pregnant. If you can convince your sperm donor to turn up and... donate... whenever you need him, at-home insemination has high chances of success. If you are using a sperm bank, the situation is a little trickier because many sperm banks require vials to be sent to a fertility clinic. Some banks will ship straight to your home address as well, though. So, how often will you need to inseminate?
The answer is, of course, as often as possible. Vials from sperm banks are expensive, so you might want to limit insemination to your most fertile days if you are using a sperm bank. If your donor is known to you, and happy to assist, you can start inseminating up to five days before your predicted ovulation, and two days afterward. You can just "suck" the goods up into a syringe (without a needle of course!) and then inject yourself, or have your partner do it. Afterward, lie down for twenty minutes or so with a pillow under your bum to push those swimmers in the right direction. There is some evidence that you are more likely to get pregnant if you have an orgasm following insemination, so you can keep that in mind too.