We use condoms during fertile times, sometimes we just abstain. I track my cycles on http://www.mymonthlycycles.com
and they tell you when you are fertile. I also get preggers very easily so I extend my fertile days by a few days from what they say, both before and after my ovulation time. So far its been working for us :) We have been using this method since 2/07. I had to wait about 4 months before I could track my cycles properly because of coming off the Mirena, we used condoms everytime during that time frame.
Example of my extending of fertile times:
My last period was 7/22
They said I was fertile from 8/2-8/6
I extended my fertile time to 7/31-8/9
My next period is due 8/19
I know it doesn't give you much condom free time but I feel it works best for us. My DH always pulls out too even if I am not fertile.
You can try ovulation predictor kits so you know when you ovulate. I don't know if it can work to prevent pregnancy but I dont see why it can't. Mymonthlycycles.com says not to use it to prevent pregnancy but so far we have been good doing it.
My DH is going for a vasectomy at the end of the month :)