This achievement is obtainable through My Player mode.
To get the achievement, you need to firstly create a player (which will see you nab the "birthday" achievement) and then guide him through 3 draft camp match-ups, as well as 6 skills drills.
The six skills drills will give you extra skills points to incorporate into your player's make-up in order to improve their skills. The three match-ups are full on 5-on-5 games involving your player and nine other players drafted into NBA franchises before the 2010/11 season.
In each of the match-ups your play starts with a "C" grading, and must improve it through good play, to at least an "A" grading in order to virtually guarantee you will be drafted in the first round.
To guarantee a first round draft slot, achieve 3 straight A+ ratings in your games.
As a reference point, I played through the three games once, achieved B or B+ grades and as drafted early in the second round. Currently I have played two A+ games and am slated to be drafted in the middle of the first round.
One thing to remember is to not get your overall grading confused with the three tasks or targets that are set for you at the start of each of these games.
Achieving these tasks is no guarantee you will receive the grading you require to be drafted in the first round. In fact, in many ways, they are unrelated - you can actually achieve 1 or 2 of the three and still get an A+ grade, while achieving all 3 might still only see you graded a B or so.
Three other things to remember are:
1 - increase the length of your game in your My Player preferences (at the start of My Player) to 10 or so minutes, while decreasing the sim game length to 1-2 minutes. Longer games allow you to gain better stats and recover from mistakes, while shorter simmed games will benefit you later on when you make the league and are striving to be named Rookie of the Year, MVP, etc.
2 - Find a camera angle you are comfortable with. This will allow you to play to the highest standards you can (including on defence).
3 - In the My Player preferences at the start of the experience, turn auto save off. This will allow you to have a trial run of some of the skills drills - and maybe even a game - and not have them autosaved if you play poorly.
As to achieving the A+ grade itself, your attitude should be to play good solid team basketball and fulfil the roles and responsibilities your on-court position requires - not unlike playing a game of Team Up through NBA 2K11's online modes.
The game is a harsh marker - mistakes such as letting your man score, being out-rebounded, making bad passes and taking bad shots all attract big deductions to your overall mark; arguably moreso than the bonuses awarded to you for good play.
What constitutes good and bad play obviously depends on the position your player plays, so I won't go into extensive details here. But be prepared to work hard for a whole game and be actively involved in the play both at the offensive and defensive ends.
Personally, I have played as a PG and have a number of techniques that have seen me notch games of 21 points/9 assist/2 blocks, and then 19 points/17 assists/2 rebounds in back to back games with a minimum of turnovers.
This has seen me get two A+ grades while defending John Wall and minimising his impact (but boy is he quick!)
Happy to share these PG techniques, and discuss other ideas, in the comments below.