Make sure the pots are warm. If the soil is around 80 degrees and you water the seeds, it's basically fool proof. I don't think it matters much if you water before or after planting the seeds, as long as you give them a good intial watering cause of air pockets. I water after planting them and I've never had a problem. I did about 100 tomato plants from seed this spring. Keep them warm and moist and they will pop out. It is common for seeds to take 1-2 weeks to germinate. Don't give up on them, just keep trying to improve their environment. Let us know when they pop out.....