Many of my attempts don't make it past seedling.

I think you're overwatering them and thus drowning them. They don't need a lot of water, what they need is humidity - and NO NUTES. I only grow autos and I grow in ProMix because I prefer to control the nutes they get and when they get them. Here's MY method: I put my seed in a glass of water for 24 hours or until they start to crack and sink to the bottom (I do NOT wait for the taproot to emerge). I then take the pot they're going to finish in (I prefer 3 gallon pots and autos hate being transplanted) and moisten the soil in the center with PH'd water (between 6.0 and 6.5), poke a small hole about 1cm deep and place the seed in it and JUST cover it. I then invert a pot saucer over the top so it is in complete darkness and place it in my tent with the lights on for warmth (you could choose any other WARM area) and I wait for 3 days before checking on it. If it has popped, the saucer comes off and is placed under veg lights or, if outside, shaded light. I take a kitchen hand towel and soak it in water (this can be tap water) and encircle the seedling so it is in a lot of humidity but still has access to fresh air. For the next couple of days, I only water that towel - some of the water will, obviously, soak into the soil but far away from the seedling. When the first true leaves emerge and become strong, I will remove the towel and lightly water out away from the seedling so as to not disturb the root structure... watering AWAY from the plant will encourage the roots to grow to find the water... At this point, you can also get rid of the shading - if you're growing in a tent, keep the lights at LEAST 18" away from the plant as it will grow trying to get TO the light. Then it's just a matter of giving it a little drink when the soil dries out making sure the PH is within range... NO NUTES for about 2 weeks and then only 1/4- 1/2 strength. Good luck... you CAN do it!