Is it better to take your custom design t-shirt decal (label) and put it on heat transfer paper yourself, or send it to a company who'll make the decals for you (then you'd press them onto the shirts yourself). I'm just getting started and would appreciate any company names you've worked with that are reliable. Thanks.
If you have the equipment, why would you have someone else do it?
If you don't have the equipment, then it works fine either way. You can either invest in the equipment and time in doing it yourself or just outsource when you need work done.
I don't think either way is "best". They each fit different needs and different business models.
I'm just getting started and would appreciate any company names you've worked with that are reliable.
There's a list of companies that can do it here:
http://www.t-shirtforums.com/heat-press-heat-transfers/t4095.html
I'm not exactly sure what *exact* service you're asking for (you're saying decals, but then talking about heat transfers, which are 2 different things), but the link above should give a good list of companies that can do custom transfer work for you.
It sounds like just a mixup of terminology. What you are calling "decals" or "labels" are probably just custom "heat transfers" or "plastisol transfers".