When my girls look at the pictures I have taken over the years they do not see many with me in them. They find lots of pictures of themselves and plenty with their dad. But where is mom? Surely she was present for all of those events and special moments. Of course she was. Right there behind the lens.
We all have plenty of reasons to not want to be in front of the camera. No make-up, hair's not done, still have a few pounds to lose, really not dressed for it...blah blah, blah. If we used the same criteria for our kids we would never take their picture either. But if you really think about it, our family does not care one bit about those things. They love us for who we are and they want to remember the moment with us there, in the photo with them.
Learn to use your timer. A tripod is also helpful but not necessary. You can always find a bucket or box or something else sturdy enough to hold your camera still so that the whole family can be in the picture together. Make sure to take at least one group shot with everyone in it at every event.
And my favorite idea...let your kids take pictures of you for a change. It's fun to see yourself from their point of view. They will LOVE being the photographer and I promise that you won't care in that moment what your hair looks like. The memories of these reverse photo shoots will be some of your very favorites.