Normally, I try to stir the wort carefully while bringing to a boil. I am putting a lot of direct flame on the bottom of the boil kettle, and I do not want to scortch or burn the wort on the bottom of the boil kettle. I also need to watch the hot break carefully. Hot break is the initial boil of the wort, and it can cause a lot of foaming and VERY easily boil over. Once you are past this, then you need to start the Boil time clock for hop additions and keep a nice easy boil (avoid covering with a lid, as part of the boil process is to drive off steam and tastes).

Always boil with the lid off. A good rolling boil is best, and you are counting on getting some evaporation, so don't worry about losing steam. Boil times vary from 60 minutes to 90 minutes. Normally, I try to run 75-90 minutes on all grain batches, and count on around 12-15% evaporation per hour for losses. Your mileage may vary, depending on how aggressive your boil is and how your boil kettle is shaped (wide squat kettles will tend to lose more steam/hour than a taller one).

Hop additions at this point are critical to monitor. Longer hop boil times lead to more bittering and improve hop utilization. Flavoring and aroma hops should always be done late in the boil or at flame out.

Boil time is also a good time to begin cleaning up the mash tun of the spent grains and rinsing it out (you can use some of the HLT water to run a final bath of hot water through the mash tun as well to cleans all the sugars out of the valves, etc. I also get the HLT temp up to 200'F just toward the end of the boil to run a 5 minute cleaning/sanitizing bit of water through the counter flow chiller. Even though you should have cleaned and sanitized this prior to the beginning of the brew, it is good to run one last high temp bath through it (without the counter flow cooling on). This should sterilize the path one last time. Also, now is the time to rinse the chlorine out of the fermentation vessels and get them drying upside down.

From now on, keeping contaminants out of the wort is CRITICAL. Do not allow anything that hasn't been sterrilized to come into contact with the wort. The idea here, is to get the wort cooled down as fast and close to 70'F as possible to minimize chance of contamination by native yeasts. Some people use an immersion chiller, which is just basically a big long roll of copper tubing with cold water running through it placed into the boil kettle. If you do, I recommend putting the chiller into the boil kettle 5 minutes before flame out, just to help sanitize it. Personally, I like the counterflow chiller, as it can cool a little faster and in a more closed system manner. On hot days, my CFC is a little too short to bring the wort all the way down to 70'F, so I set my carboys in an ice bath, which helps lower the temp a little as you transfer into them. This is also where I aerate my wort. I have a small stainless steel 0.5 micron aeration block that I've plumbed directly inline in the outlet of the CFC. I connect a bottle of pure O2 to the port and fine bubble pure O2 into the wort as it enters the carboy. This dramatically helps fermentation take off, but does cause a significant amount of foaming.