Couple of random thoughts from me:
1) I tend to leave the Garmin on my bike outdoors for a while before heading off. Gives it a chance to get a signal if you turn it on plus I find the elevation point is more accurate if the unit is at outdoor temperature as opposed to thinking it's 10C higher for the first few KM. Maybe the two aren't linked but I think they might be.
2) If having elevation inaccuracy problems you can "set" points outside your front door and it adjusts when you pass through them.
3) Keep in mind some of the display options can't be set if you only give them 1/8 of the screen - e.g. the graph showing if your HR is going up or down. I think it might be the same for the graph plotting your altitude when doing courses, but I've never used courses on mine.
4) Not sure if it's automatically on by default (don't think it was on my Forerunner 305 previously) but make sure to turn on the setting whereby it notifies you with a beep if you start moving without pressing "Start" - avoids being a few KM down the road and realising you've lost out on stats!
5) To save myself the hassle in the future, as I upload files to Garmin Connect I also save the ride file on my PC for future reference. It's useful if for example you switch to using Strava or similar at a later stage. It's not easy to transfer your history between websites so I try to keep my own copy of each file.