Past winners of the race have statistically fallen into a narrow band of age, weight and form and once you can identify which horses fit the trends, you can narrow down the field and look more closely at the horses with a realistic chance of winning.
Focus on horses between the ages of 8 and 11 years old. In the last ten years, all winners have come from this age group.
The weight a horse carries is a very important factor as obviously the horses carrying the biggest weights will find it much tougher going than those who carry less. Trends suggest that horses carrying more than 11-03 will struggle around the demanding Aintree course.
Also look at a horse's form and pay close attention to jumping ability. Though entry criteria stipulate that a horse must have placed in the top 4 in a race of 3 miles or more at least once, those that consistently place should be favoured.
Once we've whittled down the entries using the stats above, we are usually left with around 15 horses that fit the bill. From that list, we can start selecting our tips and our aim is to give you four or five horses we feel will be in with a shout at the last fence.
Closer to the date of the National we'll round up all the tips from those in the know.