'05 intermittent won't crank - start

[axxense]

Hello All. Picked up my first H2 a couple of months ago and love it, but, have just had my confidence level go way down... ...turn the key - nothing. Had it for a month and had no issues, whatsoever.

All electrical appears fine (lights, dash, etc.), yet, it doesn't crank, at all - turn the key and get zero crank. 1st time it happened, it started (cranked) about 10 minutes later. The very next morning, same thing - then it started about 2 minutes later. It then was 'fine' for a couple of days, then same thing - this time it started some 4-5 hours later. My battery tests fine at 13v. I torqued down the connections and did a test lead and it appears I have juice going to the starter. After tightening the battery and starter connections, it was fine for about a week - thought I had a corrosive/loose connection. It is doing it again now, though.

Ignition? Starter solenoid going south? Gearshift-in-park sensor/switch?

Can someone tell me of some things to check and how to check them (as if you are talking to a 2nd grader cuz I can be a moron)? My nearest shop is some 45 miles away and would rather make a good try taking care of it myself before having a mechanic charge me an arm and a leg to troubleshoot. If I can narrow it down, at least I can save some $ by doing the troubleshooting myself, if not actually fixing it. Thanks.