You should really read the forum from time to time. Every newbe gets told the same thing:
Decide what position you want to train (big or small), then get some trainees to fill the training spots, then wait till they get better. The other spots you can fill with older, but decent and cheap players.
It doesn't get you anywhere training stamina the whole time. So, my advice, wait for the draft and hope to get a nice trainee there. Then get one or two more on the TL and start training them. Very soon, they will become the best players of your team.
If you have questions about something, check out the forum.
best wishes:)