If you have any experience competing internationally you probably have your own methods. This page covers how I go about it.
This is aimed at someone with one goal for world cups: earning US points. If your only goal is to improve your world ranking, then you simply go to the 6 weakest WCs your schedule and budget allow. But most of us are concerned with getting the most US points possible. As explained in the "How Important Is My World Ranking" page, your world ranking is an important feature in earning US points at a WC, don't forget the two goals are linked.
It's assumed you'll go to all the NACs. If National Championships conflicts with a designated WC, you have to look at how many points you're likely to add to your total with each one, and go to the better opportunity.
In the past, there were 5 to 7 designated WCs, and you basically had to go to all of them to get the most US points possible. And they were normally the strongest WCs in the season, meaning you had to go to as many weak WCs as possible to improve your world ranking as well. This could easily lead you to select 12 WCs you want to attend in a season. You get a lot of competition experience that way, and a lot of frequent flier miles, but it makes maintaining constant employment a challenge and is very expensive.
This season (2003) for Men's Epee there are 17 designated tournaments, on the condition that it has a SF of at least 1.0, and only your best 5 results count as add-on points. So you have a lot of flexibility in choosing where to go. Now you can, if you are brave or a very consistent fencer, make an entire season from 5 events.
The first thing need to do is figure out what SF is the optimal one for you to earn the most US points. This is discussed here. The rule of thumb is that the best tournament for you is the one where it's so strong you can just barely make the 32.
Now you need to predict the SFs for all the designated tournaments in the season. I have made a first attempt at this, which you will find at the bottom of the SF Prediction page. Adjust the values based on what you see in your own crystal ball.
Once you have predicted SFs for all of them, rank them by how close their SF is to the desired SF for you to get the most points.
Beware that the curve for the number of points you get drops off steeply if the tournament turns out to be slightly stronger than optimal for you. I.e., if you don't make the 32, you don't get many points, if any. If you aren't fencing quite as well as you predicted you will have the same problem. This is the hard part: picking tournaments that are strong enough but not too strong.
At the core of your season are the 5 events where you will get your US points.
If you have 5 or fewer to go to, pick WCs that are just below your optimal SF, so you can be better assured of getting points from all of them. A few points from each WC is better than a lot from one or two and none from others.
E.g.: 16th at a 1.0 doesn't earn quite as many points as 32nd at a 2.0. But if you go to two 2.0s and have one good and one slightly off day you might get a 32 and a 64, earning 644 and 200 points. While if you go to two 1.0s and have one good and one slightly off day you might get a 16 and a 32, earning 600 and 322 points. Same fencer, same quality of fencing on two days, more points for the weaker WCs. Some might consider this a flaw in the system, but note that if you fence well both days, you get more for the stronger WCs.
Don't pick WCs that are too far below your optimal SF. Using the same example from above but a fencer who can place twice as high up the tableau: Going to two 2.0s, finishing 16th and 32nd you earn a total of 1844 points. But if you hedge by going to two 1.0s and finish 8th and 16th you only earn 1422 points. That's over 400 points you threw away by going to the wrong events!
And beware the SF won't be exactly what you predict. Picking those closest to 1.0 carries the risk that it might actually be below 1.0, not giving you any add-on points.
Once you have picked this core of your season, you have to look at where they are in the calendar. You may have other obligations that prevent you from going to one or more of them. And they shouldn't all be right in a row. Having events three weekends in a row is a bad idea, and even two weekends in a row can be tough depending on where you're traveling and staying. I would try to spread them out through the season as much as possible. At this point you may take out one of your core events and add a different one with a similar SF to smooth out the schedule.
Spreading things out is a good idea also because your financial situation might change or obligations may come up preventing you from going to some WCs later in the season. You could be injured and forced to take off one or more months when you planned to be competing. You want to get some results under your belt while you're able. The boycott situation in 2002 is an example of an unpredictable factor that might prevent you from competing where and when you want, we are lucky it didn't go on longer than it did. Remember that you can add extra events later in the season, but you can't go back in time to fence ones you've missed. The moral is: don't put all your events together in one part of the season.
If you can travel more, you can add additional tournaments for two different reasons: weak ones to improve or maintain your world ranking, slightly stronger ones to take a chance at hitting a jackpot in points because you have a great day on the strip.
If you're adding a weak tournament, you probably want to add the weakest one possible, or the weakest Grand Prix, to get as high a result as possible and as many FIE points as possible. On the other hand, if you have been going to all 2.0s, you may want to throw in a 1.0 where you will still get some US points as well as the extra FIE points. The higher in the rankings you are the less a few FIE points matter, but if you have a goal such as making the top 32, those few points might make all the difference.
If you're adding a strong tournament, you want to add one only slightly stronger than your ideal SF. Don't go right to Paris hoping to walk into the 32.
Note that if you can add one event, you can instead remove one event and add two slightly stronger ones. Having two lower chances for higher points can be better than one higher chance for lower points, if the odds are right. This can give you more flexibility in picking events and working out your season.
Some events are more expensive than others. Even though Montreal is a wickedly strong WC, a lot of US fencers go there because it's very inexpensive compared to flying overseas. If you can go to two cheaper WCs that aren't quite the right SF, this might be better than spending all your money on one WC.
Picking your season isn't always easy, and everyone will have different reasons for picking which events to go to. I don't set my schedule in stone more than two months ahead of time. As you see how you are fencing during the season you can better pick events to go to later on. If you have all the US points you need by the middle of the season you can focus on your world ranking for the rest of the season, or save your money for World Championships.
That reminds me of another reason to favor certain events. The USFA gives grants and an airfare subsidy to World Championships based on the number of points you earned at WCs with SFs of at least 1.5. If you earn all your points at WCs between 1.0 and 1.49, you won't be getting a grant or airfare subsidy. Just one more thing to make your choices more complicated.