Most IMP:- First read the new tatkal ticket rule post , so that u know the correct date on which u have to book the ticket.
1) Keep ur card details(which have sufficient money and u know every details of it i.e all passwords etc), ur id proof ready and put them in notepad i.e ur card number and id card number , so that u can copy and paste them quickly when required. Remember that right click won't work in irctc so copy from notepad and use control(ctrl)+v to paste.
2) keep the name of passengers ready and put them also in notepad or use auto form fill option by using them before in the irctc form for reservations so that they get saved.
3) Know the station code (Ex:- ndls for new delhi) of the From and To station , which u can get from www.indianrail.gov.in. Note:- please put the correct station code i.e in few city many stations are there so put station code for the correct station , for ex:- u want to book train ticket for sampark kranti from new delhi to bangalore so in From station give nzm (as it starts from hazrat nizamuddin and not new delhi) and in To station give ypr (as its destination station is yeshwantpur and not bangalore) if u give wrong code then u will have to undergo one additional step which will waste ur precious time
4) If possible login one day before u actually want to get the ticket and see the status of all trains , so that u will get in which train and in which class the chance of getting ticket is maximum(for ex:- if u want to get a ticket from new delhi to bangalore , then chance of getting confirmed tatkal ticket is maximum in Ac 2Tier of Rajdhani Express)
5) keep the page www.indiarail.gov.in open to see the availability status, so that u will know in which train and in which class seats are available so that u can give the train in which seats are available and increase ur chance of reservation.
6) Keep ur watch synchronized with IST.
7) check whether ur irctc account has not crossed the monthly usage limit(which is you can book 10 tickets per month)
Now that you have done all prerequisites now open the www.irctc.co.in site at around 07:55 AM (try to keep 2-3 irctc login window open in case of errors) and login to the site and give ur journey details and enter, after that u will get the list of all train. Select ur train and class and then book which u will able to do only after 08:00 AM.Keep on checking the indianrail.gov.in page for availability status, so that u can update your plan.
Note:- Never do refresh when some error comes, just open new session. If by chance your money has been debited and ticket has not been done then don't worry it will get credited in 2-3 days u continue to book ticket again.
I Hope these techniques will increase your chance of getting a confirmed tatkal ticket.