Tikka has built quite a name for itself in the past few year for making accurate, dependable bolt action rifles right out of the box. In fact, some argue that it is the most accurate, most dependable, and smoothest bolt action factory rifles in the price range.

I am inclined to agree, as I have multiple Tikka rifles, and I have not had one single cycling problem or one with bad accuracy yet. Also when looking at the PRS shooting leagues of other countries where custom actions are more expensive and harder to come by like South Africa, there is no other factory action that features so much among the top shooters like the Tikka actions.
That being said, as with anything, there is always room for improvement, and to truly get a factory Tikka to custom precision bolt action level, here are the improvements and upgrades I always do and recommend.
Stock or Chassis

Tikka rifles come in a variety of stocks and chassis from the factory. If you buy a Tikka Tac A1 with the factory chassis, or a Tikka UPR with the bedded factory stock, you should be good to go, however with all the other wooden and synthetic stocks, there will be accuracy improvements from either doing proper bedding on the stock, or putting the action into a chassis or stock with bedding already included. Personally for this rifles I have and the purpose I want to use it for, I really like the KRG bravo hybrid stock / chassis as it is like weight, tough to handle knocks and scratches, handles comfortably for most situations, and already had integrated aluminum bedding block. It was simply a case of taking my barreled action out of the factory synthetic Tikka supervarmint polymer stock, and bolting it into the KRG bravo at the correct torque.
Trigger
There are aftermarket trigger available for the Tikka from Jard and Bix ‘n Andy, but personally I have had great success having a proper trigger job done to the factory standard Tikka trigger by competent gunsmiths. After my trigger job was done on my trigger, the trigger pull was set and measure at 1.5lbs of force. Perfect balance for me for a combination of hunting and long range shooting.
Truing The Action

Generally, the machining surfaces and tolerances on Tikka actions from the factory are really good and square, so not much truing is needed on them. It may be good however to have it measure by a gunsmith to check. My one Tikka action only needed to have the bolt face squared, but other than that, I just lubed it properly, and it was good to go.