I've never had much luck either, but this time things are going well. Even with the balky ones.
The plants pictured are Red Pear, Tigrovy (first to the top of the cage), and SunGold (prolific bugger). The Green Zebra and Red Brandywine are still around 3' tall, throwing fewer blossoms and setting fewer fruit. But they're all fluffy and bushy and green.
I don't know that I have any special secrets other than several failed tomato attempts and a desire to finally do it right. I blame the heat for doing them in before (and, one time, mites). I thought I'd gotten a late start this year, as I've never done from seed before, but it seems to be working out. Next year I'm'a start the seeds on Christmas.
This is what I've done:
I started all these from seed, on Feb 4, in coco coir. Once they put out true leaves, I watered with a weak seaweed/fish emulsion solution. They were transplanted into red solo cups with a ~50/50 coir and compost mix at about 3 weeks. They were always in the weather, on my covered SE facing back balcony. Transplanted into the garden on March 16 after "hilling" with more 50/50 mix to the top of the cups. Plants were 8" or thereabouts. Set out with approx. 3 tbsp. Espoma Tomato Tone in each planting hole. Side dressed with additional Tomato Tone every 3-4 weeks (I'm bad about keeping to a schedule). Caged. Watered daily for first month out, then every other day (ish).
I've pulled all the leaves from the first 6"-12" up, to prevent dirt splashing on the leaves during rain or watering. I've thinned out some of the leaves to allow more space in the cages and airflow. I've pulled leaves that show more-than-a-little insect damage. I am NOT removing the suckers. I bounce my hand on the cages daily to vibrate/pollinate the blossoms. I have sprayed with spinosad after noticing flea beetles and a tomato plant that may have been infected with Tomato Spotted Wilt Virus (it was isolated, but thrips are carriers, and I have thrips too, and so the spinosad is supposed to work on them also).
Secrets? Magic? I found a 20lb bag of Espoma Tomato Tone via Ozbo.com for cheap.
http://ozbo.com/Tomato-Tone-20-Poun...lebase&cvsfa=3688&cvsfe=2&cvsfhu=383339323536