Well, firstly, you need to set a budget. Are you looking to get into F-Class shooting, which can run thousands upon thousands? Or are you satisfied with a "tacticool" setup, like my
Savage 10FLCP-K with decent optics (I personally use an EGW base with Burris Zee rings, and a 2.5-16x42mm Bushnell 6500 Elite)? It's practically useless for anything past 600 yards, but I can't hold a rifle steady for ranges beyond that distance if my life depended on it.
Secondly, you need to decide your caliber. .223 and .308 are "old reliables", and reloading components, as well as match ammo, abound. However, you'll get better performance with other calibers beyond certain ranges, such as the 6.5x55mm. As you can guess, loading for this cartridge is practically a necessity, adding another layer of compexity.
Third, you need to decide how much custom work you'd like to put into your rifle yourself, and then how much a gunsmith should take over. This is purely a personal opinion, on a money versus time perspective, and you have to decide this accordingly. I know my Savage is infinitely more accurate than I could ever be, hence why I'm holding off on any "custom" modifications.