Sorry, I just saw your reply!
When I do Group demonstration, there usually are 8-10 5 star prospects. I scout them all and put 4 and 5 star potential ones to the top. I usually get 3 or 4 good potential draftees on the top. Then if I have some leftover points, I scout some more, but with very little luck. Usually the best I find are among the Group demonstration candidates.
All 3 of my HOF draftees were 19 YO, since I draft by potential. 18 YO are better cause you get 2 years of Youth trainer, but this season 19 YO draftees get a bump in skills to make them more appealing. If you plan to train long term, 19 YO ones are OK.
Hope this helps!