You only tried 4 times? It took me at least 20 times in my living room before I finally got it right!!
I started using a disc wheel to cut the tubing, then using misc. grinding bits on my dremel to chamfer the edges. While this would, occasionally, make a really good flare, most were horrible (the cut wasn't square so the flare tool would get crooked and the whole thing would just bend over).
I finally started making consistently good bubble flares using the following technique:
1) Cut tubing with tubing cutter. Go slow and make sure the section of the tubing you are cutting is straight!
2) Chamfer the ID and OD using a tubing reamer. The one I used is from McMaster-Carr, part number 2709A12. This will make consistant chamfers for repeatable flares.
2.5) (added because of comments) PLACE NUT ON NOW!!!
3) Perform flare. When I attach the tubing holder, I also use a C-Clamp to provide additional clamp-up on the tubing.
4) Remove tool and inspect. It should be pretty close to perfect. If not, repeat.
When I replaced the brake lines on my car (all of them) using this procedure, I only had to do about 12 flares (8 for the car and 4 screw-ups). This is how I learned to make sure the tubing was straight when cutting...
Hope this helps. Flares take time and patience. If you start to get frustrated, walk away, forcing it won't help!