well, i take it a few different ways. i have been running a mentoring program in the GLV in tark for about a year and a half. you get a lot of variation in how much help people are interested in getting, so the first thing i would suggest, is go into it open-minded and flexible in your expectations. also, i generally don't get totally rookies, so i'm not sure exactly how much translates. i will try to share my experience to give people some ideas they can use in their own mentoring, but i am sure there are many good and different ways to be a successful mentor, so i would like to stress, play around and find what works for you (and the other party), there is no magic formula.
the first thing i do when somebody joins the mentoring program is send out a few write ups i've saved. its basically analogous to a new coaches guide except for a bit more advanced audience. i have 1 for recruiting, one for scheduling, and one for team setup and analysis/game planning. they are probably about 7 sitemail pages each, so its not a ton of detail, but hits most of the major concepts. for example, the recruiting write up i use covers a generally approach (stressing the importance of pre-recruiting planning, building a vision for your team, planning for need, thinking ahead multiple seasons, etc), and then goes on to cover the difference mechanical aspects, like scouting (with the different eval messages), dropdowns, pulldowns... the goal is to establish a baseline of understanding so that people know the options available to them, and so that we can build intelligent conversations off a reliable foundation of understanding. generally it is left up to the coach to ask me to expand on a topic if he is not familiar with it and needs more info.
from there, i mostly leave it up to coaches to come to me for help. the major exception is with new engine changes. probably 2 or 3 times after the last big engine change, i wrote up my thoughts on the changes, and how to compensate for them, to try to give the group a head start on the changes. also, from time to time (once or twice a year) ill go through and evaluate someone's schedule, or their recruiting class, etc, based on the need i feel.
so outside that, its all up to people to ask questions. when they do, how do you handle it? i try to give as much information about the approach to solving the problem as possible, as opposed to just giving the answer. that said, i will at times spend an hour or two going through their player game plan, depth chart, and team game plan settings giving them all the changes i would recommend. but, for every change, i go through the thought process i am using, leaving the answer for the end. and i often ask a coach to first give me his thoughts on his general strategy for his team, why he is using the lineup he is using and the like, so i can try to cater to his perspective, or so i can identify root causes of problems, instead of just the end results that need to be different.
anyway, there are plenty of ways you can approach the situation - proactive, reactive, whatever it is, im sure there are a ton of ways to be successful and to help people out. the most important thing is to be friendly and leave the door open, avoiding the negativity that sometimes is used in helping rookies here in the forums. also, with a really enthusiastic guy, from time to time, challenge them to do better. say hey, you are doing a good job, but i know you can do better, why don't you take some time to think about (insert area that you think he could improve on). a guy who really wants to get better will take this lead and will go explore the area, and can really benefit from this.
finally, i agree with OR, you can often learn a lot from being a mentor. if nothing else, the other guy will often ask questions you haven't explicitly tried to answer, and that can be very enlightening. or if you are trying to analyze his team for him, he may have aspects to his team you don't usually have in your normal strategy, which may open your mind to some possibilities you can use for your own team. so it really can be a rewarding experience in a number of different ways.