A good way to keep Guard numbers increasing would be to stop the idiotic policy of losing a rank when you cross services to join the Guard.
True-but in fairness, guard members who go on active duty are often stripped of a rank. Guard members don't get promoted based on points-like their active duty counterparts-but on slots available and it can take quite a while to make rank in some units. It would be hard to recruit new guardsmen if they felt that they were always going to be a rank behind another soldier who came from active duty after a short hitch regardless of who was the better soldier. The whole promotions system in the guard stinks, but I don't have any better ideas.
That doesn't always happen. It depends on the available slots in that particular Guard unit, or at least in that particular state, since states can fiddle with their authorizations between units.
I went from active duty, to reserve, then to guard, then a 3-4 year break, and then back to reserve (I'm of course speaking of participating/selected reserve, I was in active reserve the whole time. I wasn't in the Guard long enough to be promoted, and wasn't yet eligible when I went reserve the first time. The second time, I was promoted as soon as I'd served one year, and they backdated the Date of Rank, with back pay as well.