l am considering climbing Mt. Whitney with some friends.l understand that Spt-Oct is the right season.If anyone has ever done it, can you give advice on do is and don'ts?

Thanks!

You should check out the alpine institute - a climbing/expedition company. They have lots of good material.

http://aai.cc/default.asp

I've done Denali West Buttress with them, its an intermediate level climb - 21 days, but be prepared for a little longer total trip time (rest, layovers, shopping). l was 38, & had been doing a lot of leg work & aerobic work (high altitude cycling & racing), & did over 20 14K climbs in Colorado in the months prior to get in the required shape. Its required that u get in great shape, have good mountain climbing skills, high altitude experience, & experience climbing ice.

Good luck - Its the most amazing view in north america.

Take your time getting to the top and drink lots of water.
You may want to consider backpacking in to Trail Camp and spending the night to acclimate to the altitude.
It is a pretty good trail, but those 90+ switchbacks above Trail Camp are a bear!

BTW - get to the ranger station early so you can get a permit ( l am assuming that you do not have one yet).

l climbed Mt. Whitney in 2001. l started at 2 in the morning and l got down at 1 in the afternoon. l am very fast. You can do it in one day, but you have to start early, and hope there are not any storms. l do not like to carry a lot of stuff with me, but the views are very nice, and this would be a good mountain to spend the night on.

1) Get acclimatized to the high altitude. Either stay at high altitudes in other places in the days before the climb (try nearby Cottonwood Lakes), or figure on spending the night on the trail to Mt. Whitney. Drink lots of water. If u do suffer from bad altitude sickness, GET OFF THE MOUNTAIN OR GET DOWN LOWER.
2) If you're spending the night, reserve ur permit way ahead of time, because the Mt. Whitney trail climb is one fo the most popular in the entire USA. You can reserve online, but do not expect that u will automatically get it for the days u want to go.
3) Day permits r easier to get but it means u will have to make the climb in one day, & u can only get them on the day u leave, not the day before, at the local Lone Pine ranger station.
4) Unless you're absolutely sure u can get off the mountain on the same day, be sure to bring warm clothes for the night. It will get freezing as soon as the sun goes down.
5) Understand that u will be climbing 6,000 feet from the trailhead. Have u done anything like this before? There r very few places east of the Mississippi River that even have mountains that high from sea level. Half of the people who try the trail never make it. The most likely reason why u will fail is failure to acclimatize to the high altitude. The trail starts at higher than anything east of MIssissippi.