SOLO PLAY AS A GUARDIAN
With their legendary toughness and ability to handle multiple attackers simultaneously, Guardians are one of the very easiest classes to solo. While other classes have long inductions which can be easily interrupted by getting hit from several different angles, Guardian combat skills are all instant. Getting attacked from multiple sources means multiple possibilities for block or parry reactions, and the Guardian has plenty of area-effect attacks that can soften up those surrounding foes.
Guardians have plenty of options for soloing - they can go all-out DPS swinging a big two-handed weapon, or approach battles conservatively and defensively with a shield, or a combination of both styles. Actual style will vary from player to player, but the basic elements remain the same.
For raw, brutal DPS, it's hard to beat Overpower. Defense is sacrificed somewhat, as shield skills are unavailable when wielding a two-handed weapon, but parry reactions are still possible. Overpower also costs a bit of survivability: Catch a Breath, a very useful self-heal, is tied to the block reaction, which is unavailable without a shield (but can be opened up with traiting while in this stance). On the other hand, the fights don't last as long, so the Overpower Guardian can afford to sacrifice a bit of survivability, especially for sporadic, non-sustained fighting during quests and deed-grinding and such.
The conservative approach favors defense over offense. With shield and one-hander equipped, block reactions are opened up, allowing powerful, stunning blows. The conservative Guardian has a broader selection of stances, enabling him to increase his chances of blocking or parrying, or increase the amount of threat he generates. Threat generation is not a particularly great concern for soloing, except for those quests requiring the player to escort NPCs through dangerous areas and keep them from dying. It is also useful in skirmishes for keeping soldiers and NPCs alive. Even the aggro-magnet, suicidal sons of Elrond can be kept alive in the Ford of Bruinen skirmish with judicious application of threat-building skills.
With the conservative style of play, the Guardian can apply lots of bleeds and stuns to keep the fights in his favor. This requires a bit of careful timing, keeping track of skill cooldowns, enemy buffs, reaction chain openings and enemy inductions. For example, when the Guardian gets a block reaction, he can use Shield Swipe right away to open up Shield-Smash, which can stun the enemy... but will that enemy use some kind of induction skill that can be interrupted with a stun? If so, it may serve well to delay the use of the reaction skill and spread it out, so that the stun can be applied when it can be used to even greater effect.
Combining conservative and overpower styles often involves swapping gear and stances mid-fight. The Guardian will equip a two-hander and toggle Overpower stance to engage the enemy, throw a few big hits with Brutal Assault and Force Opening to activate the parry response chain, then switch to a more defensive stance and equip a shield and one-hander to finish off the fight. This style of fighting requires a keen sense of timing, but when done right it is quite effective against tough single targets or groups of mobs.
For skirmishing, regardless if it's done solo or in a group, there is no really compelling reason for a Guardian to have any kind of soldier other than a Herbalist. The fighting-type soldiers don't really do enough damage to merit the effort needed to keep them alive when they pull aggro. A Sage might be of some limited utility, keeping a few mobs crowd-controlled long enough for the Guardian to tear down lieutenants, but is less useful in general than a Herbalist. The Herbalist will spam heals and power while the Guardian does all the work, just like in a real fellowship.
As easy as it is for Guardians to solo, they must still exercise some caution. While other classes have very powerful "panic button" skills - Hunters have Desperate Flight, Captains have Last Stand, Lore-masters have Wisdom of the Council, etc. - the Guardian's "panic buttons" are more subdued. It is quite possible for overzealous Guardians to pull too many powerful mobs at once and get overwhelmed, without having a quick escape. Guardians need to go into each battle well-prepared and ready to take a trip to the rez circle if the fight escalates beyond their planning. Guardians will need to carry lots of morale and power potions, as well as plenty of remedies for disease, wounds, poison and fear.