Do a search and you should find charts online to show what blood types can result from parents with specified blood types. For example, I'm O-, so I'm pretty much a blank slate -- I could choose a donor with my blood type (which make for a very limited donor pool) or either allele of my partner's blood type.
This actually turned out to have been an issue for me inasmuch as I gave the Czech clinic where I cycled my blood type, but we were using DS and my partner actually did not know his blood type (and I planned to tell, so I didn't care). But when I didn't specify a blood type for my SD, the clinic unilaterally decided to choose O- donors (remember, I'm a blank slate, so ED had to be O-, too) as I didn't state that it didn't matter, and only about 8% of Caucasians are O-, so that greatly limited the donor pool and I got a BFN.
When I realized what happened, I was so paranoid that they might overlook or ignore a request that blood type didn't matter that I went to Wikipedia and looked up the largest blood type group for central Europe and gave that as DH's blood type for my second cycle. BFP.
All-in-all, even though we're pretty much tell to the world due to my age, I wish we had known DH's blood type -- he has had something like five major surgeries; how the heck did he not know? I've donated gallons of blood, so it's hard to imagine not knowing.
Maggie (in VA)