There isn't a way you can guarantee yourself a new player by opening packs, so you'll have to grind levels in order to recieve more packs.
Personally, I found this the fastest way to earn experince.
All you need to do is hit 3 3-Pointers. The first will count as 4 points for being the first basket, the other two will net you 3. Rinse and repeat until you level up.
Use any players you want, but I'd reccomend playing using players with a high 3-Pointer rating, as well as against players with low block/steal ratings, in order for you to be able to score easier.
Alternatively, you can play through the tournaments to earn more packs, which have a higher chance of containing rare players.