Drive around and repair turrets as engineer. You get about 0.5 to 1 cert per turret. Why the differance? Because you get an exp multiplyer the longer you stay in a region. So when you start out repairing the first turret in a big base, you are most likely getting no modifier, but after 10+ minutes you should be somewhere at +15 or +20%. Which of course increases your exp gain. 250 exp is one Certpoint. If you manage to find a big defense and focus on repairing turrets, or drive to the hindland and repair save emplacements on a big base, you can easily make 20 certs per hour. Option 3, is to follow big defenses and play an Engineer. Play ammunition runner. Zip around the place and wherever you see 5+ people shooting at something, drop them an ammo pack. Repair the MAX units that usually retreat when they are badly damaged and tanks if they retreat as well. But remember to repair from the side. Don't stay behind or infront of the tank to repair it. Also an option is to get the Ammunition Cert for the Sunderer and follow the a large Tank column. You can combine that with the driving around option and following the offenses of your faction. When there are 3-4 tanks that are fighting anything, you can easily make a bunch of exp for resupplying them. But its not risk free. Sunderer are a big target and they give alot juicy exp. But honestly, all 3 options are sub optimal. You should get twice that amount if you do something fun. If you look for people with VOIP, that organize themselves, you should be able to get kills and assists, as well as healing exp or resupplying exp, with a nice juicy Squad Exp bonus. An Organized squad makes at least twice as much certs as the above mentioned 20 certs per hour. It does. At least the stockweapons do only give 1.