If you're very likely to have one of the worst records in the league, then yeah it can be worthwhile to invest in the draft. Drafted players give you more merchandise income, which in effect lowers their salary. And even in D4 leagues, probably not a huge amount of managers are investing a lot in the draft, so you can easily get a good player.
First, I would suggest deciding whether you want to train guards, or whether you want to train big men. Stick to one kind for now. Many people recommend training guards, as they can be expensive to buy on the transfer list. But bigs are good to train too, so I think it's whatever you prefer. Once you decide that, wait until closer to the end of this season, and when the deadline for playoff eligibility is over, then prices on players will decline. At that point, buy veteran players for the positions you're not going to train. In terms of USA D5, respectable to strong skill levels are decent. Know that at 33 years old, guys can start to lose skills.
Then, I'd probably spend the rest of this season giving a bit of training to Dutton, Marshall, Pizarro and/or Davis (depending on what you might train next season). These guys may never be long term starters, but they could be backups, and as your initial team players, they're counted as home draftees with respect to merchandise bonus. I'd personally choose the guys from those who have good defense skills, and then train either jump shot, or one on one training for the rest of the season.
For the draft, would suggest doing the 10 point scouting combine. This will let you see the ages and heights of the prospects. You'll definitely want to get an 18 year old player, as age affect training speed quite a lot. Then you'll see who has appropriate heights for your choice of guards or bigs (think 6'4" or less, or 6'10" and above, respectively). After that, invest in 2-3 scouting points for the next couple weeks, and "scout" a few guys with your desired height (that's 1 point each). If you find a guy with 4 or 5 orange balls in skills, you could consider spending 2 points to get an estimate of his potential. Then rank him high and hope you grab him!
Ok, I've rambled enough. Any more questions just shoot!