Ro Zeny has more allure for many players because if you have it then you can do more things also can level up quickly. How to train skill rank the fastest. It will be based on magic as primary skill tree and sword and secondary.
1. Optimal Equips
I would recommend getting a +2/+3 skill set. +4 skills are nice but expensive. So you can afford it and I think that it is a good deal, go get it. I would also recommend getting a+6 skill exp weapon or two +3 skill weapons. Also, get the highest level jewelry that you can equip.
2. Go get yourself the crappiest blades you can get. Then go to get a mob that gives you semi-low damage. Cast regen or any other useful buffs on yourself. Hopefully you can get AT LEAST an 11 combo.
3. Combo Ideals
Try to get excellent always. Excellent gives +20% skill exp
If you can not get excellent at least go for a good. Good gives +10% skill exp.
Take the times skirling to practice your combos. When you reach 11 try to time it so you hit the skill a few milliseconds before the required zone.
4. Alternate Ways to Skill Level:
1) Punching Technique - Sadly most people do this not knowing that this is one of the slowest ways to skill
3) Other Things Not To Do - Do not mob! I do not know why the hell people do it but you will not get ANY extra skill exp from hitting more than one monster. Do not raise the skill level of any skill you are training with over 9. What we want is lowest delay. Not highest damage. Do not over buy adept.