There are two ways to approach the Leage racing; one being to turn up on race day and maybe get in an hour of practice prior to the race using a quick setup or anothers' setup downloaded form the web, the second being to develop a setup suited to your own style during the week. If you want to be competitive for the race then you're going to need to practice. Be assured the top guys do; even those that already have a setup from previous races at the same circuit.
Before you start any analysis, it's a good idea to grab the F1Speed tool, which you can incorporate into your test runs while driving to give a quick feedback loop on any setup or driving line changes.
Here's a basic strategy for developing a competitive car for a race weekend.
6 Days out
Befor you contemplate making your own car setup or analysing different driving lines, you neeed know the track and to be able to lap consistently. Start by loading up F1 Speed and use it's data to help you gain consistency at a particular track. Make use of the average lap value to try and get your fastest lap, your average lap and you current lap as close together as possible, over a decent number of laps (at least 15).
Start with the middle Quick Setup and put in enough laps so that you lapping consistently as detailed above. This is your baseline. Without this there is no point in starting to investigate custom car setup.
Once you are lapping consistently you can begin to modify your car setup. Start with the wings, trying them in various combinations such as high downforce front and rear, high rear/low front, high front/low rear, low front and rear. Each time you make a setting that doesn't feel horrendous from the outset, give it a few laps to let your driving style: braking, turning and throttle on points adjust to the new car balance. Sometimes you just know that the car is going to perform worse, other times it might feel worse on corner entry but exit the corner faster. Use F1Speed and F1PerfView to see the real difference each change makes. It's hard to judge a half second or so, and over the whole lap, a few tenths lost or gained here and there can add up to a big change in lap time.
After wings, repeat the process for springs, then ARB, and finally use alignment to fine-tune car handling, particular corner exit. You'll also need to revisit the gear ratios to make sure your hitting the rev limited in top gear on the longest straight. Check out the guide on setting up your gearbox for more information.
5 Days out
Long Run Day. The aim for today is to establish tyre wear and fuel consumption given your car setup. Remember a fully fuelled car is gong to handle worse than an empty car. You may need to raise the ride height to counter the extra weight. Fill the car with 20+ Laps of fuel and prime tyres and set out from pits. Build up pace and heat in your tyres, feeling the extra weight of the car. Remember today you're just trying to understand how long you can go on a set of tyres. Ideally aim for 1 stop during the race, and the races are about 25 laps, so you want to get around 17-20 laps from a set of tyres and a 20 lap fuel load.
4 Days out
Time for some fun. Bolt on some options, drop your ride height, suck your gut in and man up, it's time to try your qualifying pace. Set your fuel mixture to rich, and perform a slow out lap, then hang it out :D
3 Days out
While we'd like for it to always be sunny, with clear skies, nature isn't always acommodating. Start a new Grand Prix with a fully wet setting and repeat the steps from 6 Days out. I wouldn't worry too much about a qualifying time. Get used to the wet weather handling and work on your race setup
2 Days out
Somewhere in between bone dry and soaking wet, will lie intermediate. If you're happy with your dry setup and ok with your wet, try some intermediate running. Repeat the steps from 6 Days out. If your dry pace is still wanting, continue days 6 - 4.
1 Day out
Have a beer and rest.
Race Day
Log in an hour before race start to check your game install, your wheel, and your mic. An hour should give you enough time to correct any problems (such as low batteries, or a misconfigured wheel). I'd also advise doing 20 or so warmup laps.
You can also reduce your workload by sharing duties with your teammate.