well it actually depends on the cash you are willing to invest.
I take it you are wanting to go with a NA setup which is what I want to do. so things that I have thought about are Type S pistons, rods depends really because the type s are not that diff from what Ive been told from stock H22 but shotpeening them would be smart, micro polishing the crank, having block gone through by machinist(honing/measuring clearances,ect)
Then you need to stiffen the valvetrain up with either a prebuilt head from JG engine dynamics or other suitable builder//or putting in titanium retainers/springs, port and polish, polished valves, and then if $$$ is avail you could put in camshafts but this could wait depending on funds.
NA is unfortunetly expensive

Hope this gets you started.
Also you have to think about fuel supply and such and engine managment.