I have spent a lot of money so far on my account on various skins and such, but to be honest sometimes after I don't play on some of them I feel like I have wasted my money and RP on skins that I actually don't like.
So if you don't have enough RP or don't want to spend money on skins! Here is awesome and free legal way to have all skins in game, the program is called Skin Preview, it gives you every skin available in the game for your use.
I mean nobody except you can see the skin but its really useful to have it, also it has thousands of custom skins in it too!
This is the YouTube video with the instructions on how to use it and download.