I've been there. I get so focused on how to start that I delay and delay, like I am focusing on that first tree in that hypothetical forest (the saying can't see the forest for its trees? I get stuck doing the opposite and lose touch with the forest - the overall picture, long term result because that first darn tree is so foreign to me.)
What I did? I started to count calories right away and made sure I stayed around 1200 - 1600 (my BMR was/is around 1800 - 1900, the amount you aim for depends on you). I then started to attempt those 100 pushups, 150 dips, 200 squat challenges found on the internet. It helped me get my mind off of the whole "How do I start losing weight" thinking and put it on to actual numbers and a set goal to reach in a set amount of time. It got me thinking about my overall fitness rather than all that fat that has been stressing me out (as well as how awesome it will be one day if I run into someone who brags about being able to do all that stuff and I can do the same - or more.) The losing weight part took care of it self during this "starting phase" of my journey.
Did I ever accomplish those online challenges? Yes and no. I can do hundreds and hundreds of squats, but still can only do about 15 push ups on my knees, 6 proper. But it doesn't matter any more because it got me past what was holding me backing , that whole "I don't know what to do with myself to see results" thinking. (I also had a knee injury I had to come over that I used as an excuse, but that is no longer available to me as the exercise corrected that issue.)
Now I have moved on to other stuff. Once I got over that how to start hump I find it is much easier for me to 'know' what to do to continue on my path.
Height 5' 5" | BMI 26.2 | HW - 202 (2010) | SW - 192 (07/09/11) | CW - 157 | STGW - 149
GW - 130 | H waist 41.5 | S waist 40 | C Waist 32 | G Waist - out of the 30s