Okay first guide, the first time i played Hecarim it was in 3v3, i went 20/5/13 and i was criting like a boss. so don't be to harsh on my guide. please leave constructive criticism if any, don't just downvote my guide.

He benefits from movement speed so naturally you want to have ghost, my preference for the second spell is heal because i can stay in the lane longer and help if you are trying to get away. But for sure go with Ghost, second is really up to you.

Start with BOOTS and 3 HEALTH POTS. The boots i recommend for Hecarim are BOOTS OF SWIFTNESS, then build zeal. Then work on a PHANTOM DANCER and a BLOODTHIRSTER. The PHANTOM DANCER will buff your movement speed, attack speed and gives you a bonus crit which makes it valuable, by the end of the game i usually have two built. If you go my way and build two, build a TRINITY FORCE before the second PD. The TF will benefit everything so thats a must as well. Now i was only able to build these five before the game was over, although before it ended i realized that a YOUMUU'S GHOSTBLADE would really add on to him, so if you can try to work that in there if you want.

Overall Hecarim is a strong champ, at the end of my first game his stats were
AD- was about 300
AP- didnt really matter but close to like 50 i think
AS- 2
Movement Speed-524 flat!
and crits were up to 550 every few seconds laawwwl
i ended the game with 20/5/13.