This post assumes you're looking to get your Private Pilot License (PPL) to fly recreationally; if you're in it to start a career as a pilot, different advice might apply.
Have high standards when you look for a flight school in your area. What are the planes like? Are the people cool? What do students think, and why did they choose that flight school? What are the hourly rates? Getting your selection of flight school right could save—or cost—you thousands, so think through it.
You'll also have to choose between two types of schools: "Part 61" schools which adhere to a set of regulations which give more syllabus flexibility, and "Part 141" schools which are far more rigid. If you're in this to have fun, then a Part 61 school is probably your best choice—you'll be able to adapt your schedule around your strengths and weaknesses.
If you're looking for a slightly more ordered and militant approach, then consider using a Part 141 school. Also, Part 141 schools have a lower hour requirement for licensure, so you may save money going this route. Be careful though, because not many people are ready for their PPL checkride at the minimum hour mark.
Aviation is costly. Airplane rental will be between $100 and $200 per hour, and expect to pay $50-100 for your instructor as well. This means that you should have access to about $10,000 to get your license. If you have to take a break from your training schedule for financial reasons, this will hurt your momentum, which could make training even more pricey.
Timing the interval between lessons is an art, and it depends on your availability and your training goals. Ideally you should be training at least once a week. If you wait any longer, you risk forgetting what you learned in the previous lesson. Some say the sweet spot is two lessons per week, but everyone has a different opinion. Figure out what's right for you, but don't spread your lessons out too far.
A large number of flight instructors hate their job, and a large number are terrible at their job too. Don't be afraid to talk with management if you feel like you need a new instructor, and even be prepared to switch flight schools if you need to. A mediocre instructor will pass on bad habits to you that are incredibly difficult to break.
Most training flights last about one hour long and involve training for several maneuvers. You should be mentally prepared for each maneuver before you even leave the ground. For the most efficient training, don't let your instructor surprise you with new content in the air (beyond a reasonable level).
Then once you're on the ground, make sure your instructor discusses what you did well and how you can improve—in my experience this dialogue helps your progress to "stick" and not get lost between lessons.
By your checkride, you will be expected to act like the Pilot In Command (PIC). So act like it—take control of the situation and show the examiner that you have executive decision-making skills.
Examiners have to see you remember to perform clearing turns before each maneuver. Don't forget them. It's easy to.
At the end of the day your examiner just wants to get your money and be assured that you won't call his judgement into question by crashing an airplane. So if you act like a level-headed and methodical person, the examiner might overlook a minor mistake or two.
You may have to postpone your checkride for weather—several times. Wait for good conditions, and if weather does deteriorate mid-checkride, don't feel pressured to continue! Try again tomorrow.
Have fun, find a great instructor and become a pilot. And remember: being good is easy, not fucking up is hard.