The great Charles S. Roberts was working out of his garage when he gave the world the first set of Avalon Hill titles. Tactics II was the noble son of an earlier work known as "Tactics" from 1954. Since that time, players have sought more historical battles then just the idea of "Red" versus "Blue".
However, having played this game now for over 50 years, and winning one of the tournaments in the mid-1990s where Tactics II was featured; I have come to know that almost no one really understands how to mobilize and use the units properly!
If we look back prior to 1973, and consult the 1958 and 1961 editions, it is a little more clear in the rules as to how "0-5 HQ" units and Specialists should be played. Now what brings me to this point? Well, quite frankly, players tend to spend the first turn leaving their initial set-up areas, move units to the middle of the board to defend bridges, waterways, etc. and then try to flank their way through into enemy territory. This concept generally will make the game rather tedious and long running, without the fireworks that were originally intended in the "Blitzkrieg" ideology.
This game should be fast moving! For example, if Red has the opening move, on the first turn the Blue Capital can be contested with ONE mountain unit. The extraction of this pressuring unit will take the best effort or luck to get rid of it.
Paratroop units and Amphibian units tend to be used by average players as a type of "Ranger". They will move them to an isolated beach and march them up to a city or take the paratroopers and use them to drop behind the main lines and increase odds from a "2 to 1" to a "3 to 1". Although this is OK, it is far better to use these units for the "isolation" rule or ensure destruction of an armored unit by surrounding it with ZOCs.

Headquarters units were originally a "span of control" counter for individual corps. They also carried the nuclear missile options and each was different in what effect they carried. Now, they are used to garrison lonely cities, front line drones, etc.
Mountain units are powerful. They can control roads, especially in that area on the left of "Reds" territory, where there is one lonely mountain next to a road. Remember: Mountain unit ZOCs cannot be entered. So it negates the road access. If a paratroop unit is dropped on the city on the first turn by Blue, then he can rush a ton of units down the area and cut off the Island while attacking the initial set-up areas of Red on that turn. Subsequent battles will be fed by back up troops continually coming in by sea to that city as the original rules set that there is NO LIMIT to the amount of units that can come in by sea to an uncontested city that is captured even in the same turn. (This is almost always forgotten by today's players)
So a sweep invasion that cuts off the Red Island can be done and those bridges are not as easy to take back as a player may believe. Units on the Island become trapped and eliminated in two turns!
I once witnessed a tournament player conduct an invasion on turn one with Red through the forest road! Of course he was bottled up quickly and his attempt to flank the Capital of Blue never succeeded. Simply the rule that allows you to bring in reinforcements by sea in an unlimited way will prevent any invading army from getting to you and splitting Blue in half. (Unless you contest the Capital on turn one with your mountain unit! SEE.....)
Also, remember in tournament play that there are NO replacements every third turn. So eliminated units never come back. What does this imply? The Armor units should be eliminated as soon as possible. I have seen opponents forget this basic idea and lose 5 Armored Divisions before they woke up! Then of course it was too late. Suicidal one to one attacks followed by "4 to 1 " or better attacks on my turn forced surrender very quickly.
So please fellow gamers! Before passing judgement on this game consider if you are really playing it right. Too many "Follow the Leader" ideas result in missed opportunity. Fluidity is the key to this game and most offensive minded people using the pieces properly will bring quick victory against average players.