Best of luck HeatedEnd!
I would actually recommend buying oldies just low salary oldies. You can get rid of the deadweight and find serviceable 30 year old players for really cheap. Just make sure the salaries are less than 10k (max) per player. Try to stay around the salary floor in the first couple seasons because you won't be winning a championship any time soon. But its all about finances and building an arena.
The reason id recommend starting with oldies instead of 24 - 29 y/o players is that they are cheap. You can get the same player at age 32 he would be $50 000 and at age 26 he would be $150 000... Cheap quick upgrade will hep you start winning some games quickly and it will help your finances because more people will show up at your arena. But don't spend just save, build arena, save, build arena, etc...
Thats just my take on that. If you ever got any question message me. Good luck!