I consider myself a very unexperienced jungler. I've been trying to practice jungling with various people like Mundo, Olaf, Fiddlesticks, and Xin Zhao. Right now I think I'm pretty good with Olaf, I can get through the whole jungle in a custom w/o a leash, which I must say is quite an achievement for me as I usually fail horribly with other junglers.

What I wanted to ask more experienced junglers is on their experience/preference on what to start with on Olaf.

Machete or Cloth for items?
Axe or Vicious strikes for skills?

What would you say is the best way to start on Olaf?

Right now I can't really afford new runes, but my current runes are:
G Destruction mark(6.3 arpen, 4.3 mpen)
G Att Speed Seal(4.59%)
G CDR Glyph(4.22%)
No Quints( I know, sad)
They are pretty general and work as a versatile rune page for all champs.

Machete/undertow

Position yourself so that when you throw the axe, you're picking it up again. then you can pretty much spam it, and clear the jungle even faster.

Mostly stick to AD, and armor runes for any AD champ though I think your masteries are more important than your runes. Sorcery and mastermind will give you 14% cdr. Runic affinity will allow your buffs to stay 20% longer, and resolve will give you extra gold from smite.

When leveling up you can focus on axe, or reckless. If your team already has cc then reckless, if not then you might consider leveling up undertow. I prefer ganking w/ reckless.

where are you having problems w/ jungling?

Ghost and Smite
9/21/0 or 0/21/9 masteries

ARPen Reds and AD Quints, Armor Yellows, MR/Lvl Blues.

Axe first, Vicious Strikes second. Some prefer the opposite but Axe provides better ganks if you can land it.

Machete + 5 pots first.

for runes, this is pretty standard good AD page:
9 atk dmg mark (t3)
9 arm seals (t3)
9 mr/scaling mr (doesn't rly matter which) (t3)
3 ad quints (t3)
Works for most jungler, NOT THE BEST, but is good. Seals SHOULD ALWAYS BE armor.

ALWAYS start machete x5, cloth "helps 4 ganks" but the HP you save from clearing camps fast w/ machete is better than cloth.

you max Q because slow goes up as levels : so more slow 4 ganks.

So, how i play: (tl;dr)

machete+5 hp pot start
9 flat atk dmg, 9 flat arm seals, 9 flat mr glyph, 3 flat ad quint (all t3)
max Q>E>W taking level 1 Q level 2 W level 3 E then rest Q>E>W

With Olaf, I struggled(before) to kill red buff in a custom(without leash), I'm sure I can with a leash on blue.

I just tried the build with machete+undertow. I managed to clear the whole jungle in a custom(without leash) with a slight adjustment to my path. I usually go wolves->blue->wraiths->red->golems but this time I went double golems before red. What do you suggest for a path as Olaf?
I also remembered that smite works with the spell vamp from vicious strikes, which is totally awesome.
Out of my 5 potions, I use one during wolves, 2 more during blue, and 2 during red. All without a leash in this case.

What build do you guys suggest with machete?
Madreds razor is stronger than spirit stone at first but the Spirit of the Ancient Golem/Lizard Elder items are superior to Wriggles. I would rather build a different item from vampiric scepter anyways.

I'm also not sure whether frozen hammer is a better choice than warmogs. It is good for sticking onto a target but in an ideal situation I would hit my axes. Plus the immense regen from Warmogs feels like it's worth it.

tl;dr
Currently I go Wolves>Blue>Wraiths>Golems>Red, any other path suggestions?
Wriggles vs Spirit of Ancient Golem vs Spirit of Lizard Elder
Frozen Hammer vs Warmogs

Thanks for the great replies everyone! I feel much better in the jungle now than before.

You're path is good. If you're having trouble it's either you're not using undertow right, or your masteries are horrible. I'm assuming you're not using undertow right. Olaf can pickup the axe from undertow, and it'll cut the CD in half. If you throw it right you don't even have to move to pick it up.

Everybody I know builds Ancient Golem. It gives you some pretty good sustain allowing you to roam longer. This means you level up faster, and gank more often.

I pretty much build Hammer right after golem. You've already got some good health regen from golem, and getting away from olaf w/ hammer is tough.

I don't suggest vampiric scepter or any vampiric items on olaf. Once you hit 18 vicious strikes should be enough to keep you well sustained. Focus more on armor, mr, and damage.

Wolves -> Blue -> Gank -> Wraiths -> Red -> Gank

Machete 5 pots.

You pretty much NEED armor yellows to jungle well.

Max undertow first.

And you shouldnt stress so much about being able to clear the jungle without a leash, almost every jungler that can do it, finishes with like 100 hp (except high sustain like warwick, or Nunu, or someone like Shaco and his boxes).

A bit of a non sequitor, but you mention fiddlesticks. He has one of the easiest jungle sustains ever (though the new jungle is a lot slower for him than the old jungle). And if you're trying to practice without a leash, Fidd is often better off without a leash (unless it's a dedicated sustained damage aid), because of the way his drain timing lines up (light damage to blue golem is less life for Fidd to drain).

As everyone else noted, Armor Yellows are mandatory, and the best yellow runes you can get. Get them.