Thats more than one mod! lol
As mine had the toyota legana kit, coilovers, work rims and muffler when I bought it, I would say, the first mod was putting the standard exhaust back on as it was tooo load and hardcore for me.
I reckon the first best value for money mod would be a muffler, then induction kit. Then some arb's or coilver (depending on money)