Disclaimer
I would like to start off by saying I'M NOT THE BEST SPEARMAN EVAR, these are just tips for newbies that I've grasped over three years time of playing a spearman.
Let's begin.
There are 5 main areas you will want to focus on as a pure spearman.
Speed
Speed is one of your greatest assets as a spearman, and if not used effectively, your enemies will wipe the floor with you. I recommend having at least 6 athletics, any less than this and you will be too slow in group fights. Use your speed to outmaneuver shielders and good blockers, to get behind them and swing at their backs. The faster you are, the harder to hit you are. If a fight is not going that well for you it can also be used to "tactically fall back" to your teammates and regroup. Your speed will also play an important role in dodging arrows.
Momentum
When thrusting with the spear it is important that you get a running start at your opponent. If you just stand still and jab at them it's not going to accomplish anything. Whenever you go for a thrust attack, quickly back up and move forward, this will increase the speed the spear pierces them, and do more damage. (Also you feel pretty badass jumping from a castle wall and stabbing someone in the face, one hitting them because of your momentum.)
Be Unpredictable
This will largely effect how well you do in group fights. When engaged in a group fight, break off from the person you are fighting and stab someone else. Use your speed to move around and stab people who do not see it coming.
Outreach Your Opponent
If you are using the war spear, (my weapon of choice), it has 150 length. So use your reach to your advantage whenever you can. Normally you can dodge a one hander, quickly step back, and swipe at their feet, which will make them disoriented and vulnerable for a second attack;(preferably a stab.) Also it is important NOT to thrust when you are within punching range. Your spear will most likely glance off of their body, leaving you unable to block and vulnerable to an attack.
Morale and Focus
This is a hard one to explain. Being a pure spearman requires a certain "state of mind". You cannot play this class effectively if you are not focused. When you are in a 1 on 1 fight, ignore the environment around you, and picture you and your opponent alone. Apply all of your focus and you will usually emerge victorious. If you go into a duel and are worried about a nearby fight, you will not be thinking about how you can best your opponent, you will be thinking about how the other fight is going. I like to picture morale and momentum as being the same thing. Whenever I am running along a castle wall, I do not stop to engage in a duel. I keep moving forward and jab at anyone in my way. If you do not kill them you will have at least wounded them for a teammate. Don't run at them with your spear in thrusting position, click at the very last second and stab them right in the freaking skull.
Playing Support
This is pretty self explanatory. When you are in a large battle where 2 battle lines are clashing, stay back and jab at anyone who raises their weapon. Stay behind a shielder or a good two hander. When they engage in a fight wait for the enemy to start attacking, thats when you get on their flank and stab or swing at their side.
While you are in the rear of your teams battle line, you can also keep an eye out for cavalry that charge at your teams rear. Cavalry tend not to see a spear, as it is much harder to notice than a pike. Any weapon with 141 length or more will make a horse rear, so a war spear is perfect for this. A plain spear only has 135 length, so it's not the best for going against cav, but it's hella better then fighting them with a sword. Once the cav is reared perform a backwards jump and stab the rider in the back.
Equipment Choices
When playing as a spearman I typically go for 30-40 body armor, I'd say 43-45 MAX. Any heavier and I feel it effects my speed too much. Your helmet should be something with 40 head armor or less, anything more is overkill really. I usually find leather gloves and boots to be satisfactory.
This guide was mainly focused for the War Spear, but I suppose it also works well for the Red Tassel Spear, Spear, and Ashwood Pike. (The red tassel is a bit faster than the war spear, but loses some damage btw.)
I also suggest having a cheap short sword on hand, for those close quarter situations indoors. I prefer the short arming sword, and it's not even 4k.
With these new tips I hope all you people new to spearhood (yes i just said spearhood) can perform well on the battlefield. Have fun and remember to poke poke poke!