1. Do a thorough engine warm-up before you spin up the rotors. Most people I have seen that do not do this end up flying with an engine that hasn't had a proper warm-up.
2. Get familiar with the "process" for your gyro. Practice the process several times before you try to actually start the rotors. For example, in the GyRonimo, it is necessary to climb up on the seat to reach the rotors and climb back down quickly, start the motor and move forward. This is no small task, but is mitigated by a set routine of foot and hand placement. Some machines require the motor to be running. Foot and hand placement, as well as a good wheel chock or brake routine is important for that process. Many machines require the stick to be held full forward to prevent a rotor strike or flap in wind. Make sure you have clearance with your head and helmet for your process. All of this needs to be worked out in advance.
3. Face the gyro into the wind. Starting the rotors with a crosswind could turn you over. Starting the rotors with a tailwind could be pointless, as the wind will be working against your efforts.
4. Start pushing the rotors slowly. This isn't a race at this point. Push each blade for the first few revolutions, then switch to every other blade once the speed comes up. Now it is a race. Timing is everything. The goal is to go "as fast as you can." If you have some wind helping, then you may quit as soon as you see the rotors coming up on their own. In fact, if you notice a rotor speed increase that you are not personally responsible for, you must stop, get seated and keep the stick at an appropriate angle.
5. The appropriate stick angle once seated depends on wind. If there is no wind, full back is generally required (though I tend to keep the rotor a smidge off the rear stop as it is easier to feel a coming flap that way). For wind that is keeping the rotors going for you or stronger, use the stick as a throttle. Forward to slow the rotors, back to speed them up. Of course, any sign of flap and move them full forward. Be careful not to let the rotors drag you backwards. You may not have sufficient braking to stop this with wheel brakes. Just push the stick forward to stop any tendency to go into reverse. Operating a gyro in reverse with the rotors spinning is an accident waiting to happen.
6. Begin moving forward. If your rotors have not started spinning up yet on their own, because you aren't getting any help from the wind, then move slowly. Your first goal is to move forward enough that you don't lose any RRPM you just worked so hard to create. The best way to lose it is to move too fast and cause a blade flap. A low speed, no wind blade flap "probably" won't flip you over, but it could. It could also certainly bend things up, and on some machines cause the rotor to strike the tail, causing a really bad day. So, once you are sure you are moving forward with a gentle breeze in your face, and are sure the rotors aren't slowing down. Add a bit more power. Just a bit. If the rotors start moving faster, you've got it. Repeat the process of adding just a tad more power until you get 80-100 RRPM. If at any time you feel the least hint of a flap, reduce the power and push the stick forward immediately. If you catch it in time, you can generally recover and continue, otherwise it is generally best to stop the machine and start over from scratch.
In all cases it is best to make your first tries in the presents and under the supervision of someone who knows the machine and has done this before, such as a CFI. This is not only for the purpose of getting the rotors spinning by the most practical and efficient methods, but for safety. I'll be the first one to say it is possible to get rotors up and flying while making a host of safety blunders that, but for blind, dumb, luck, could have ended badly.
That said...mechanical pre-rotators are a good thing!!!