1. A passport. A passport book (cards work at land crossings, but the book is safer if you ever fly home in a pinch).
2. An FMM tourist permit. Mexico's entry permit. Get it at the INM (Instituto Nacional de Migración) office at the border crossing. Stop, park, walk in, fill the form, get stamped. Free for stays up to 7 days; around $40 USD for up to 180 days. You can also pre-fill online at the INM website, but you still must stop for the stamp. Riders who blow past the border without one are fine until they hit a military checkpoint or fly home, then it's a problem. Just get it.
3. Mexican liability insurance. Your US policy is void in Mexico, and liability coverage from a Mexican-licensed insurer is legally required. Buy online before you leave (Baja Bound and BajaMex are the rider standards). A week costs roughly $50–100 for a bike. An accident without it can mean detention until fault is settled. This is the one item with zero flexibility.
No TIP. The Temporary Import Permit for your vehicle, the deposit-and-paperwork process mainland Mexico requires, does not apply in Baja. The whole peninsula is a free zone (Zona Libre). Ride your own bike the length of it with just the three items above. You only need a TIP if you put the bike on the ferry to the mainland at Santa Rosalía or La Paz.
Tecate is the rider's crossing: small, calm, minimal wait, INM office right there, and it drops you straight onto Hwy 3 or the Compadre Trail dirt. Mexicali East is the efficient choice for the San Felipe corridor. Tijuana/San Ysidro is the big, chaotic one. Use Otay Mesa instead if you must cross there. Cross early morning, on a weekday if you can.
Northbound is the slow direction. Tecate is usually under an hour; Tijuana can run 2–3+ on weekends. CBP wants your passport; expect a couple of questions. No fruit, no fireworks, and declare anything you bought. If your FMM was multi-entry/180-day you keep it; 7-day permits get surrendered.
Cash is king. Pemex stations in towns take cards, but ranchos, camps, taco stands, and the gas-from-drums guys do not. Carry pesos (get them from a Mexican bank ATM for the honest rate) plus small US bills as backup.
Fuel strategy: the corridor rule is top up at every Pemex once you're south of San Felipe or Ensenada, even at half a tank. Gaps run 100+ miles and a station being “out” for a day is normal. Rancho Grande at Gonzaga and Villa Jesús María are the famous corridor lifelines. Verify they're pumping before you depend on them. A 1–2 gal fuel bladder turns range anxiety off entirely.
Phones: most US plans include Mexico roaming near towns; the interior is dead air. Download offline maps (Gaia, OnX, organic maps) before crossing, and carry an inReach or similar for the empty stretches, it's the desert Southwest rule, just with fewer bailouts.
Military checkpoints (retenes) are routine and professional: kill the engine, lift your visor, expect a quick look through a bag. They're looking for drugs and guns, not tourists. Firearms and ammunition are absolutely illegal. A single loose round in a pannier is a serious crime. Don't ride at night (cattle, vados, no shoulders), wave at every rancher, buy something at every stop that feeds you, and pack out what you pack in. Baja has been welcoming riders for sixty years; be the reason it stays that way.
Start with Tecate → San Felipe, camp the coast on San Felipe → Gonzaga, then go deeper: Gonzaga → Coco's Corner → Bahía de los Ángeles. The full route list is on the trail map.