With all due respect, that post gives some pretty bad suggestions and doesn't show an understanding of the draft process.
There was a lot of cart before the horse advice.
Let's start with the Area Scout and dissect what he does. It's his job - as well as the other 50+ Area Scouts working for the parent club - to scour their areas for ANY player who has A SINGLE PROJECTABLE MLB tool. Leads about these players come from every source: travel coaches, personal coaches, HS coaches, showcases, tournaments, etc. The AS then scurries about evaluating these leads; some AS' even create their own teams in fall (called scout teams). (Scout teams in Southern Cal can have up to 100 players rotating in and out of games.) All sorts of approaches are used, but the idea is to find EVERY SINGLE PLAYER who fits the criteria.
From these leads, the AS essentially ranks these players in order. At the beginning of the kids' senior seasons the list FOR A SINGLE AS can be pretty long - in hotbeds sometimes 100+ HS players.
So, the TOTAL NUMBER OF POTENTIAL HS players PER CLUB preliminary identified will number in the thousands. Remember: the TOTAL number of HS draftees will be app 400.
From those identified as having a single potential MLB tool, the next stage of the winnowing process is to determine which will go to college NO MATTER WHAT. It can be family desires, the particular college committed to (e.g., Ivy and Stanford are viewed as hard and fast commitments compared to the local JUCO), maturity, anything. For the vast majority of those, the buy out bonus exceeds what the scout believes is their worth and those guys are dropped from the draft list. (Has nothing to do with talent; has to do with signabilty.) (Also, if the kid is a slot potential pick, the AS will continue to communicate as the draft approaches to make sure the bonus ask is hard and nonnegotiable; if the bonus ask comes into "line," the kid goes back on the list.)
How does the AS learn the demand? He asks - through the questionnaire, home visits, the personal coach, etc. These visits, communications, etc., give the AS insight into the recruit; is he ready for prolife, is he mature, can he take care of himself, etc. - whatever the AS thinks will shed insight into the player makeup. (At this point a family can finesse the bonus demand by truthfully saying, "let's let the season play out and well decide closer to the draft.")
So, at the beginning of the HS season, the AS has a rough idea of rankings of kids, a rough feel for who has a strong college commitment (and who can be bought out of that committment), and a rough feel for the kids readiness for prolife.
From this group (and late bloomers who are identified later in the process), the BEST OF THE BEST are marked. For these guys (maybe 100 - 200 NATIONWIDE) more attention is given. These are the guys who are slot potential (or slot equivalent [e.g., college senior slot savings which can be wheeled to a lower pick]) and who will be seen by the regional scout, cross-checker, GM, owner, etc.
These are the players who may benefit from an advisor. For these guys, there is plenty of time to find a reputable advisor (and there are far more charlatans than reputable guys). For everyone else, an advisor is unnecessary, a distraction, and provides needless pressure.
(Here is where I'd ask other posters with more current knowledge to chime in; in my son's time, if you had an agreement with an agent, you lost your amateur status and could not play college ball.)
Pressure, you say? Try being a HS potential slot pick (and you can tell simply by looking at the crowds of scouts at each game) pitching in front of GMs from 20 clubs, dealing with your GF who is angry she isn't getting her 100% attention, being the butt of HS pranks, taking tests, finessing your college coach while maintaining a strategic ambiguity about going pro, etc. I have seen countless guys simply be HS kids in this situation (meaning he is not ready - yet - for proball; only the rarest thrive under that pressure).
About end of May, the clubs create their draft lists. Scouts will then confirm bonus demands, hard college commits, arrest reports, whatever, and draft from that surviving group.
A couple of points from this rambling mass of info: without that projectable MLB tool (very rare to see in HS kids, not rare for college players), all is for naught; only a few kids will be offered or worth the unicorn bonus (but many players/families disagree).
So, what's the best advice for a HS player? Grind and improve your skills; ignore the draft. For parents, search the threads and the internet for useful info (e.g., MLB scholarship program, slot amounts, previous draft histories, terms of the CBA), realistically evaluate and understand prolife and ask: is my kid really ready for this new type of hell?
When and if the time comes, all contracts are the same (except for the bonus); there are really no negotiating terms.
Oh, and recognize if the kid gets his unicorn and two years later decides that living in 100° heat for two years, with no friends, no freedom, regimented days focussing ONLY on baseball, with constant failures in the field, is no fun and quits: the bonus is refunded to the club.
Sorry for the length of this rant.