-
start reading the journals you kept since you were seven
-
wait for your immediate environment to tremble violently
-
wake up somewhere backwards in time
-
try to fix your junkie-prostitute girlfriend, her criminally insane brother, or that firecracker prank that went awry?
And for crying out loud, make sure Jack the Ripper does not get a hold of the key.
Remember: bring extra pair of glasses.
Step 1: Wait.
Step 2: Your future self will appear with a time machine.
Step 3: Your future self will give you the time machine, and disappear.
Step 4: Profit!
Step 5: Goto Step 2
Become a miserly scrooge, make that putz Bob Cratchett work late on Christmas Eve, then go home and wait for some spirits to take you on a time-travelling trip or three.
Though I’d just offer Igon a Twinkie if he’d make a time-travelling machine. 
You could always travel to the planet Hyperion* (preferably on the tree-ship, Yggdrasil), on a pilgrimage to the Time Tombs, and hitch a ride with the Shrike!
*Warning: Don’t pick up any cruciform shaped wildlife.
Basically you put together a time capsule of such overwhelming coolness, including a tape of one of your #1 jams, that the people who open it in the future will like it so much that they’ll put all of the royalties and groupies in a time machine and send them back to…NOW!
5, 4, 3, 2, 1…Now!
3, 2, 1…Now!
2, 1…Now!,
1…Now!
Dragon Warrior VII-style time travel:
- Find mysterious shards
- Open the way to the ancient ruins by your sincere prayers.
- Fit the mysterious shards into the correct altar.
- Press the circle button.
Now, in very brief, the methods of time travel as shown in Chrono Cross:
A) Get assimilated by a parasitic life force that has been manipulating the course of human history. (It helps to have a mother with megalomanic tendancies and a kingdom dedicated to the study of magic.)
B) Capture the Frozen Flame and do various experiments on it in your ultra-futuristic research laboratory. (Beware of time crashes.)
C) Get possessed by the supercomputer FATE when you try to take your panther-demon-bitten son to a doctor, but your boat gets stranded on a mysterious island. (Say goodbye to your sanity.)
D) Defeat the Garai/Masamune-possessed Dario. Doreen will show up and change your dinky weapon into the Mastermune. The Mastermune, along with the Astral Amulet, will grant you one trip into the past. (Don’t forget to save the girl in the red outfit, so she can save you from drowning when you were a young boy.)
I seem to remember that one of the Slayers OVAs had Lina go into the past, but I haven’t seen it and I have no idea of what methodology was involved. (A wizard did it, maybe? 
)
Press the emergency button of your Tninctipn-designed space suit that activates the stasis field around your spaceship…
-discontinuity-
…and awake to find that 3 billion years have passed and an asteroid has accreted around your ship. Hilarity ensues!
Some more!
*Use the same spell out of the Necro-wossname that brought you to the world in the first place.
OR
*Drink a special potion to make you fall asleep. Count carefully!
OR
*Simply fall asleep for a long, long time.
OR
*Rescue a turtle from some mean, bratty children and accept an invitation to go partying in an undersea kingdom. (But don’t open the box!)
OR
*Break an hourglass containing the Sands of Time.
Red Dwarf
Fnd an abandoned space ship in the middle of deep space and steal it’s time machine.
Drawbacks: You must also have a FTL drive or you’ll just end up in deep space in a different time.
The Last Continent (Discworld)
Crawl through the window of the bedroom of the Professor of Unusual Geography.
Drawbacks: None as long as you don’t move the wood that props the window open.
THe Flash (DC Comics)
Build yourself a cosmic treadmill and run really really fast on it until you jump into another time.
Drawbacks: Must have super-speed.
Nit-pick. This needs to occur in Japan, near the coast. Otherwise, you get the wrong kind of turtle.
Well, if you really want step-by-step instructions:
(1) Arrive in past with instructions for building time machine
(2) Leave instructions in your favorite book
(3) Leave for future
(4) Lose favorite book without ever seeing instructions
(5) Arrive again and put the damned instructions in the safe
(6) Leave again
(7) Arrive yet again to put sports almanac in the safe with the instructions
(8) Leave again
(9) Find instructions and almanac in safe
(10) Bet on a bunch of sporting events to make money for parts
(11) Build time machine
(12) Leave for future on test run
(13) Get back from future
(14) Leave for past with instructions
(15) Arrive from past. No instructions ('cause you forgot about losing the book, remember?). Time machine gone (never existed?).
(16) Recreate instructions from memory (ooh–this is tricky).
(17) Build another time machine.
(18) Go back to past to put the stupid instructions in the safe.
(19) Arrive on test run. Cool!
(20) Leave to return to the past from test run.
(21) Arrive from past after putting instructions in safe.
(22) Realize you forgot to take a sports almanac back
(23) Buy sports almanac
(24) Head back to past to put sports almanac in safe
(25) Get back from past
Got that? Dang. One of these days I’m going to have to write a time-travel story. Remember, folks. You saw it here first.
Final Fantasy Tactics-style time travel:
- Build a Celestial Globe out of old parts in Goug Machine City.
- Activate it with a Zodiac Stone (Libra or Cancer, IIRC)
Just don’t ask me why the blond spikey antisocial jerk’s Material Blade somehow ended up on top of a volcano. 
Bob and George-style time travel:
Either:
- Upgrade your gun so it can create dimensional vorticies or
- Have your local alcoholic scientist invent one.
- Prepare a long, convoluted explanation to your past selves that they won’t understand until it’s too late.
It isn’t necessary to bleeping hate time travel, but it helps.