I try to read as much as I can about the topic and I seek advice - both in-person and on the Forums - from those who are more experienced than I am. I practice by myself. I do not see how this is any different from seeking knowledge and becoming proficient and skilled at anything else in life.
I pay for professional training. I do not see how this is any different than going to school and learning from teachers.
I want to know that I will have the proper knowledge (including of the law) and the right thinking to first be able to avoid confrontations and bad situations, but I also want to have the confidence of knowing that if it ever came to me having to draw my pistol or sling my shotgun, pull my knife - or even grapple on the ground - that I've done everything I possibly can to insure that I will go home or my loved ones will be safe (or can escape).
As with tradja, I truly feel that it's the best money I've spent in this area. I've spent good money on quality firearms. I've invested heavily in good gear. I've dumped a few thousand dollars' worth of my chosen HD/SD ammunition down-range, to insure that they function properly in my firearm and that I'm comfortable with them, and understand their shooting characteristics. I'm not going to cheap-out on training. It's expensive (for me, it's the child-care that gets really expensive), but it's worth it, and to my friends, I'll say to them that I think it's absolutely necessary.
Ah, yes, grandpa and grandma. I truly love them dearly, but unfortunately, their lifestyle also means that it's hard to guaranty that they will be able to help. Yes, when push comes to shove (like when childcare fell through the afternoon of my low-light course, they stepped-in, without any complaint, and kept Anna for much of the day), they're there, but I don't want to overly burden them.
Don't you worry, I'll get there and to TDI, some day. And sooner rather than later, I hope!