1. Plan well ahead!
Too often I am approached with little time to make the improvements needed. Long and complex races need many skills and physiological changes that take time. Multiple buildups are often needed. It's fun but there are no shortcuts. A person’s background affects this time period but often a seven day race or a 100 mile run at altitude will take a years prep at least. The time is an investment to allow you to succeed after all that money and travel!
2. Get help (unless quite experienced and even then, you may benefit from one for some time).
It will save you time, money, injury and possibly even failure to finish that 100 mile run you have set your heart on. We usually fail, unless something exceptional happens like a fall or virus, for a reason. Those reasons can usually be narrowed down with experience or Coaching. To be plain it's taken me forty years to learn to my humble level and it never stops. If I have raced your race two or three times I would hope I can take some of the pitfalls away from your first effort or improve your time dramatically. Even experienced athletes realise they need to optimise their training time, reduce injuries or recovery from injury quicker. So, find someone (that is the trick) who has the skills you need, can impart them to you (that's different from same programme to everyone) individually to make you better. Coaching is a personal relationship which goes both ways, have a good look around as being a great athlete is not the same as a great Coach. Having six degrees and Coaching qualification is also no guarantee you are an effective Coach. Take the time to find someone and then have faith in them.
3. Equipment and modification.
Over the years I have travelled the world to some of the great races. Poor kit choice is obvious in all races – don't get me wrong, the kit is wonderful and expensive but it's not right for the race or the person. These races are on specific terrain which often requires changes to kit, special kit in some cases. Some of us are not preparing our kit well or we are buying the wrong things. We are sitting at a laptop and looking at the internet and being sold the wrong kit by companies and reading material put forward by poorly informed back of the field athletes or top athletes who are paid or given kit or who weigh half your weight. Be careful being sold commercial solutions from bars to packs to bladders to shoes and gaiters. I have seen people win desert races from poor countries using packs basically made from pillow cases! The point is maybe we are overthinking it. If they can run on bags with no freeze dry sachets and no flash packs then perhaps we are getting too commercialised. Case in point I ran to top fifty places twice at MDS with road shoes (why are you assuming you need trail shoes?) and home made gaiters sewn onto the uppers. I never saw a better commercial gaiter and I avoided some of the ridiculous knee length commercial ones or the thick ones that cook your feet. There are lots of examples like this. Of course, test your kit weeks and months ahead of time... then you won't be guessing. There are loads of urban myths about these races on the internet. Be careful what you read and don't be scared to modify your kit.