I’ve played between a dozen and two dozen runs with Ardabil in 1.34.5 on VH (more than half lasted 2-3 years) and I can only second what was said above. You basically have (imo only) two viable strategies:
- Get guaranteed by Shirvan and ally Mushasha quickly and Bahmanis once you can (all improve relations/modifiers things mentioned above are necessary) This allows you to declare on small countries in Caucasus and on Ajam / Timmies quickly and take land when they fight each other or their vassals (Timmis), but you may struggle to get strong allies other than Bahmanis (I did) Even when I formed Persia it was a struggle, or
- Become a vassal of QQ (Ajam just wants land) and get independence and a strong ally later. I found that its best to become a vassal of QQ (offer it before they occupy Ardabil but when Ajam declares on you as well, because you get your cores back in that war). After that Ottos will get to them soon (they are shia and close to Ottos, while Ajam is sunni and far away), so you can get them to support your independence with dip rep advisor (and all the tricks in the book - try to scornfully insult someone other than Austria and Poland though). You can get independence with only Mamluks anyway, but you’ll have to fight Ottos soon in that case and I didn’t manage to even white peace them before building power base first even though I formed Persia. Actually, getting vassalized and having Ottos support your independence was the easiest way.
In terms of other early steps I always declared on Bispas (if they have no allies, which is like 2/3 of times) on Dec 11, with Gilan (offer land) aiming to finish war by the time Mushasha wants to ally you or QQ fabricates a claim. Making ruler a general with a siege pip or two really helps here, because you need to finish a month or two before the alliance / war (QQ may ask to release them if little time passes). 1/2 of my fails was due to this war dragging but I found that it helps if it works.
In terms of RNG, lvl 1 dip rep advisor is a must but it is not really rare. The other important aspect is if Shirvan rivals you (if so, they will not guarantee you and Ajam will likely declare on you even if you ally Mushasha so that QQ wont - they always ally Mushasha). You can rival them and go down the vassal path, but if you want to go your own way you need their guarantee. Finally, I found that QQ need to have a domineering attitude, rather than hostile, to vassalize you. If they are hostile they want land rather than vassalization. I actually couldn’t make it with hostile QQ and Shirvan as a rival, but I am not particularly good, so it is probably the reason.
Nonetheless, it is still possible to make it with the strategies already proposed above. But it is quite hard. I found that it is harder than Byz for me, but it is just a subjective opinion.