Well, the first thing thou hast to know is that thou wilt never be able to empty thy bowels completely all the time. I'm very used to go #2, and even if I take my time to finish, there's been times when I went at home as well, but I guess it can happen anytime, even going always to the toilet as well.
That said, I'd suggest thee to take thy time to go completely, it will help thee to not rush it and to let it flow naturally.
Another thing that usually helps is going #1 and trying to go #2 at the same time. Since some of the muscles control both, thou'lt surely let it go completely that way.
If anything else fails, I find some high places I can use as platforms and I lay on them and try to finish, or I find lower ones, I put a leg on one, I bend a bit and try to go, and there's always some poop that comes out while I do that.
And of course, look for some privacy and feel no pressure to go