Coming from an Edge 205 I had lots of problems with working out how to work the Oregon. Here's what I have ended up doing.
• Get the bike ready to roll.
• Turn on the Oregon, then go to Setup -> Reset -> Reset Trip Data and then Clear Current Track (this is because I will have downloaded the current track at the end of my last ride).
• If I haven't downloaded the current track, I will - rather than clearing it - save it (through Track Manager).
• Enjoy my ride, using the Trip Computer to see how I'm doing speed and time-wise this journey.
• Turn the Garmin off if I'm doing nothing for ages like sitting in a cafe or if I don't want it to record where I am. It records as soon as you turn it on - advantage is you don't have to remember to do the 'Start/Stop' button, disadvantage is you can't stop it recording if you're doing something really slow.
• Turn the Garmin off when I finish my ride, go inside and download the data onto Ascent (Track data).
For the next ride I start again, so I'm clearing the tracklog each time rather than saving it. However if I'm not going near a computer between rides I'll save the track instead.
I like to clear the trip computer each journey so I can evaluate my overall speed.
Hope this helps!