Lifters are located in the engine head and help actuate engine valves. Lifter tick can be caused by a variety of factors such as wear in the lifters, low oil pressure, or carbon build-up. It is common for older engines to tick as they may build oil pressure slowly upon initial start-up, and in colder weather. Lifter tick may not be harmful to your engine, but is a good indicator that your engine may need some preventive care.
Add Seafoam into your engine via an engine vacuum line. A good line in the one off the brake booster, which will typically be a large black round canister that sits in the engine bay, right in front of the driver's seat on the firewall. With your engine running, remove the brake booster line (your engine will stumble and idle poorly -- this is normal). Pour Seafoam into a small cup and slowly feed it into the booster line. Since it is a vacuum line it will suck the Seafoam into the engine. Allow a third of the can to be slowly ingested into the engine, then turn off the engine and allow it to sit for an hour before restarting. Once you stop the engine, reconnect the brake booster line.
Pour a half can of Seafoam into your engine crankcase through the oil fill cap on your engine. Seaform or similar engine top end cleaner will dissolve and clean carbon deposits in the head, which is the typical reason for lifter tick. It is a good idea to time this at an oil change. Run the engine with the Seafoam for a few days, then perform an oil change with fresh oil and filter. Pour the remaining half can of Seafoam into the gas tank to provide additional cleaning.
Change your oil and filter. Older oil will cause lifter tick since the additives in oil dissolve over time. By replacing your older oil with fresh oil, you will improve flow to the lifters, which will improve lubrication and reduce lifter tick.
Use a thicker grade of oil. Thinner oils, while providing better cold weather lubrication, can cause lifter tick since thinner oil drains out of lifters faster as compared to thicker oils (in the case of hydraulic lifters). If you are using a 5W-30 oil, for example, consider switching to a 10W-30 oil to see if this reduces lifter tick.
Lifter tick is ticking sound, but that sound can be replicated by any number of things such as a small exhaust manifold leak, or a timing chain. Most dealerships and independent repair shops offer top end engine cleaning servicing if you do not want to perform the cleaning yourself.