I do copious research, thinking up with esoteric questions even the experts don’t know the answers to. I keep thinking I need more information. Ultimately, I usually don’t make any decision at all because I’m overwhelmed.
I usually sit and wallow over it in my head for a long, long time…
Then eventually write, or type, it all out as a way to vent and just get it OUT of my head and somewhere else.
I like to consult other people who have been in similar situations, or have wrestled with similar decisions, and se their perspective. I like to know their history, what they did to figure out the decision, and how their life changed afterwards.
It’s all hard man. Decisions, thinking, analyzing, feeling. It’s tough.
I write it all out and then read it again later.
Can’t remember if it was Hemingway who said something like, “I write so I know what I think.” That’s exactly my process. In fact, I did it today while making a very major decision. Not fun, but I think I did the right thing.
Precisely that. Both points.
Put it off as long as possible unless that causes harm. That gives me more time to think both consciously and subconsciously about it, often after days/weeks things aren’t as big of a deal or things have changed by then.
Educate myself as much as possible so I can make an informed decision.
Occasionally if something is way out of my expertise I will ask someone their opinion, but I don’t resolve to follow their advice just listen to them.
Hilarious, I came in to say more or less this. I find the result of the toss sometimes lets me know how I truly feel about the question.
Then of course, I abide by the coin’s decision because I’d promised it I would. 
ETA: what @Hari_Seldon said; that’s exactly it.
Pros and cons, often with dollar values of how much each issue is worth to me.
Talking with a select few friends whose opinions I value.
Posting in discussion forums, usually ones devoted to the relevant subject.
Revisiting over time. Maybe this is “sleeping on it”. I like the Persian suggestion above that calls for sober and drunken evaluations (though I don’t drink so can’t use that one).
At some point I make a smaller decision that I’ve put enough effort into it, and go with the option that’s leading.
I generally feel good about the choice I made, and don’t spend much time rethinking.