Without hesitation, our favorite spear builds are the Geddon Low Profile Spear Guides by Poo and Arrakis. We would build from these to write our own, but the guides are concise and the build isn’t a very complicated one. You’ll still have to choose the right core. If you want to get any fancier than that, Sir Magnus of Taurendor has an excellent guide to adding a hook for pulling shields, a really cool line-fighting maneuver.
Spears are simple to build, there are four basic components.