Are you waiting a few days till you have a bulk of gold then sell, or are you selling daily? With suicide botting you won't know when you'll get banned so would it be better to sell daily or is it worth risking gold to keep yourself under the radar by minimizing trade?
Can I just make a private guild and just have my characters in it or do I need to run a guild with lots of members?
They do delete guilds and ban every account in it from time to time - make sure your main isn't in it if you don't want to lose it.
I am suicide botting my first account which I got for £8. Thus far my plan is get the character to level 90 asap and just go full on. I am planning on making enough gold for a wow token then starting to siphen off the funds through various methods to my main account. I will probably fall flat on my face but I'm excited to see how it ends none the less!
As to the bulking or selling daily question: you can get a decent bit (100k at the very least imo) and then start selling. I find this to be okay, because you likely won't get buyers immediately assuming you are striving for half decent prices. In my experience I would just bulk and sell when I got reasonable offers (which can take any amount of time), and would end up selling at 100-1000k at a time.