Maybe a talented regulus player can push a lane on his own, but I that is not me.  I realize that reg is for support, and tried a few ideas out.

I'm having some real luck going maximum range and maximum damage.  Keeping items to a minimal.  Getting angelic fury, using BotS to keep myself in mana.  Brutality gauntlets, wyrmskin, and slayer wraps. Mage Slayer (towards the end, obviously) and a life steal item to regen out in the weeds.

I really don't have a definitive build up, because it changes so much depending on the flow and especially the player I'm supporting.  Right off, I try to communicate with my teammates and see who responds well.  That's my man!

And a saying I've picked up, really counts:  "If your the waterboy, BE the waterboy".  You cater to your tank.  Keep at max range, so you don't become the target suddenly and he's trying to save you.  If he's retreating, throw a slow (Mark or mines).  Save his ass. 

Something that works PERFECT in this set up is a universal cube.  Heal your tank.  Keep 2 of them whenever you can spare the cash. 

My main objectives are damage, attack speed, max range, and just plain speed so you're not a liability come time to retreat.

Just some ideas to throw out there.  Probably a more efficient idea for this, probably way better reg players.  That said, I've had extremely good luck pushing this.  In 2v2 battles, been able to literally melt the enemy with the focus fire and healing the tank.  The enemy tends to get frustrated when the tank is hitting hp potions and in between that, you're healing him.  Average players tend to switch to reg and then you run like hell, ready to double back.  Takes a little intuition on that to really maximize it.  As soon as I would turn around (nearing tower, not catching reg, no point, etc), I turn and start shooting again.  Human nature must be universal, cause it's dead on 98% of the time.

Not a big reg fan, but I'm tired of watching the selfish regs cost a team the fight.  Guys that leave their teammates to chase down a kill, letting them die.  Pulling their supporting fire randomly, or firing at the wrong target.  Buying expensive items and then getting smoked by a quick target change by 2 fast enemies.  Counting on mines.  Etc, etc.

If you're going waterboy, be the damn waterboy, right?  None of that gatorade crap

And, obviously, if you get some kills, spend that money on the team!

I'm sure a lot of those that read on here don't need the advice, but I think sometimes people get jaded and lose focus.  Sometimes they let themselves go on autopilot, and you see old icarus drifting off after a retreating DG while his tank gets ganked.  Or just plain old not healing his tank. 

No "I" in team.  Though, there is a "me".  And you could spell "meat", too.