Regular Ticket:
A regular ticket is also called a full-fare ticket or a full-priced ticket. It comes directly out of the airline's ticket pool. It is issued by a travel agency using an airline ticket pricing system or directly purchased from the airline website.

You can get a regular ticket from a travel agent or directly from the airline's website or office.

Consolidated Ticket:
Because airlines cannot sell every single ticket on every flight, they reserve a block of seats for "consolidators." A consolidator is an agency or company that has a contract with a given airline (or multiple airlines) to sell tickets that come from a special pool. Most of the time, consolidated tickets are considerably cheaper than regular tickets, unless the airline is running a special/sale on regular tickets. Airlines often run special deals or price wars/reductions.

Consolidated tickets are typically much cheaper for U.S.-India trips and are mostly sold by travel agencies that are run by Indians (persons in India or persons in the U.S. of Indian origin). Usually, you cannot buy consolidated tickets directly from the airline. It may be possible to make a reservation with the airline first and then buy it from a travel agent. But this may not always work, since airlines may be overbooked during peak periods. Some travel agents buy blocks of seats from airlines.

Some agents claim to be a consolidator when they are not, and there really is no reliable way to check if an agent is a consolidator for an airline. Whether or not an agent is a consolidator doesn't matter.

You may buy a ticket either in India or in the U.S. For an India-U.S.-India trip, it may be cheaper to buy a ticket in India if you are going to make payment in Indian Rupees. For a U.S.-India-U.S. trip, it may be cheaper to buy a ticket in the U.S. if you are going to make payment in U.S. dollars. There is no harm in checking both places, though.

Unfortunately, unlike domestic travel in India, air ticket prices are not fixed and vary a lot from time to time and from agent to agent. Therefore, you'll need to do a lot of homework and shopping around to purchase airline tickets.

It might be safer if the travel agency has been appointed by "ARC" and "IATAN," is a member of "ASTA," and has been in operation for a long period of time.

If you have already booked a ticket and are just shopping around for a price, you should mention your airline reservations to the agent. Ask for a price quote only, or you run the risk of the travel agent taking over your ticketing without your prior authorization. Of course, check whether the price the travel agent is quoting is for the booking you made or for the new booking the agent is going to make. Just because an agent quotes you a price, do not expect that price to be guaranteed unless you actually finalize the purchase. Finalizing the purchase means you've agreed to buy the ticket from the agent at that price, at that time. Ticket prices can change, and most agents will quote you their current price, which may be higher or lower than what you were quoted earlier. You may mention the previous quote and see if the agent will honor it. 

Do not call several agents and give them your passenger list. If you do, many agents will book you on the same airline, and that can result in multiple bookings which are automatically cancelled by the airline, through no fault of the agent.

Also, if one agents tells you that there are no seats available, first contact the airline and confirm that the flight is indeed full, then have one trustworthy agent  put you on waiting list. Then you can wait and take chance if you desire to fly that airline on that day. Once you put yourself on a waiting list with one agent, do not call several other agents and let them put you in waiting list with the same airline for the same flight. If that happens, you are wait-listed for the same flight multiple times. When your name comes up for confirmation, most airline computers detect the multiple entries of your name and auto-cancel you. Then you will have lost your chance completely.

While purchasing airline tickets, it is safer to pay using a credit card. However, many travel agents charge 3-4% for using a credit card. It would be extremely difficult for a good travel agent to offer the same price to you whether you paid cash or with credit card. Every credit card company charges a transaction fee, and someone has to pay that fee. If you are looking for the cheapest possible ticket, you have to pay the credit card processing fee, as that is the cost that is simply passed on to you. After all, travel agents have only a limited profit margin. If your agent is offering cheapest ticket, they can't afford to pay credit card fees, as well. Otherwise, those who don't want to pay by credit card will pay a higher price because the cost of credit card processing will be added to every ticket. The practice of charging extra for credit cards may or may not be legal. You can report it to the local business authorities and the credit card company, but they may or may not be able to do anything about it.

However, it is possible to pay by credit card while purchasing regular tickets, as the airline is bearing the credit card processing fee.

Also, insist on getting the credit slip (customer's copy) after you pay by credit card. This will help you with the paperwork with the credit card companies, Better Business Bureau, etc., in case you are owed a refund and the agent gives you trouble.

To avoid paying extra on the credit card or for agents who don't accept cards, you may want to send the payment using transaction checks that credit card companies provide, which sometimes do not incur a transaction fee. If you do this, check with the agent beforehand regarding whether or not they will charge extra. Also, many credit card companies treat these checks as cash advances - you start paying finance charges the moment it is cashed. You may want to review your credit card company's policies.

Ask the agent to fax you the itinerary after you book your tickets. If the agent can't fax it to you immediately, you should ask them to read it to you to make sure there are no mistakes in names, ages, travel dates, etc. Most airlines don't allow an incorrect name change without a fee. However, if there is a minor error, like a letter is left out, they may make an exception and charge you no fee. You should contact the agent if you realize the error after you receive the ticket.

Insist on a computer generated ticket. The airline may not accept hand-written tickets, especially in the U.S. Make sure that the box marked "Status" says "OK." If not, you don't have confirmed tickets. Insist that the agent give you confirmed tickets. Don't depend on the agent to confirm your tickets for you. If at all possible, before you pay the agent for your confirmed tickets, call the airline and check that they are confirmed. If they aren't, discuss this immediately with your agent. If they are, save the confirmation number. Ask the airline to fax you a copy of the confirmation, which will usually have your confirmation number on it. It may be useful later if there is a dispute. When checking the booking with the airline, make sure you review the passenger name(s) and flights/times. Always verify with the airline(s) that the entire trip is confirmed before you leave. Confirm each and every leg of the flight individually. Some travel agents have been known to lie about this.

If you pay by check, make sure that the address on the check is correct, or the travel agent may send the tickets to your old address. Make sure to strike off your old address on the check and write clear instructions to send the tickets to the correct address.

In most cases, you need to keep calling the agent to remind him/her to mail you the tickets in time. It is best to pick up the tickets in person. Many agents send tickets by certified mail or courier service like Fed Ex, UPS, Airborne, etc., automatically. Confirm that they will do this. Also confirm who bears the cost of such mail service. Even if it costs $10-$15 more, it is well worth the money, as agents are not responsible for tickets lost in mail and it's a huge headache to replace them.

Check the backside of the ticket to see if it was altered by the agent in any manner.

If a travel agent owes you a refund and gives you a hard time about it, you may try approaching the Better Business Bureau. It works sometimes.

If you have a dispute with an out-of-state travel agent, even if you win the case in your home state courts, you must still move the case to the courts of the other state and try to collect there. Quite impractical, to say the least. It's better to buy tickets from a travel agent you can visit in person if a problem arises, even if it costs little more. It is well worth it.