Here is what I have gone through and learned so far.
To start a pool project you need: big desire to have it, funds to pay for it (it is too hard to get financing for it), place to build it (pool can be built even on a hill). Pool is not an investment. It will add only about 50% of the pool price to the house value. It will also add to your electric and water bill. It will not add to your home insurance (unless you do not have a fence), but it will require monthly maintenance, and also some part replacement from time to time. Pool requires permits, including permit from a tree department - this part should be covered by the pool builder. But from another side, pool is lots of fun. At least this is how I think now :) It is important to get bids from several contractors, read as many reviews about them as possible, check their license and projects they have built (they should have photos). Simply ask to take you to the pools they have built in the area, or ask for phone numbers of the people and call them to talk in private. When going through the bids, ask about every item! Why is it needed? Is there an advanced option? For example, outside control of the equipment vs remote. Read about what needs to be in the pool: tile, coping, heating equipment, lights, hot tub, number of jets, pool cleaning system, including little robot running on the bottom, stairs, amperage, pool shape, size, cover, etc. Ask about each of these items when going through the bid. Also do not listen to what they try to sell to you. Listen to the facts. Negotiate for everything! And the most important thing to remember is the following. You are the boss before the contract is signed. A pool builder, like any other contractor, wants your business, and will give you maximum discounts for everything you ask for to get it. Once the contract is signed, and you want to get something extra, you will pay the full price. It is not because contractors are bad people, it is simply because there will be no reason for them to give you a better price.
If you want to build a patio or a deck, it is time to get bids for them as well. Usually pool builders partner with landscape contractors, and they will recommend them to you (make sure you get landscape bids without pool builder's price mark-up). Talk to them as the whole project should go smoother if you work with well partnered companies. But make sure you get bids from other contractors as well. It is your money and you deserve the best deal. Just like with the pool bids, ask about each little detail. Everything needs to be questioned: material - basic vs colored vs special shape or stamp, drainage, type of wood or pavers, pump for concrete, and whether it includes stand-by and hose length, removal of your current concrete or pavers, etc. Make sure they take you to the projects they have completed. Nothing will ever compare to a couple of live pictures.
If you want to add lights or plants to your project later on, think about them at this point as well. You may need to get conduits put under concrete or pavers to be able to put electric or water pipes through them from one side of the backyard to another, and you will not be able to put them afterwards.
Think, think, think. Do not let anybody pressure you. Before the contract is signed - you are the boss.