Battleaxes are better than Longswords until you can consistently do 21 damage a hit.
This is actually wrong. +to hit is the hardest thing to get in the game now. Longswords get a +3 proficiency bonus to the axe's +2. That's actually a big deal.
More generally: +to hit is precious. Make getting it a priority.
Starting attributes are very important. Your primary attack attribute should be at least a 16.
Any attribute that doesn't start at 16 or higher and doesn't constantly get pumped at every opportunity will not be worth using on attack rolls - plan ahead, know which attributes you'll be using for attack rolls, and plan accordingly. (Also, some classes feature a variety of attack powers using different attributes, plan a path that only takes powers which use one or two attributes - you will not be able to support 3 attack attributes, and two leads to heavy focus on those attributes so you may want to limit yourself to one).
Your secondary attributes may be important - know how important and invest accordingly.
Be able to target multiple defenses so you can take advantage of enemy weaknesses. (Average defenses for monsters in the MM from high to low are fort>AC>refl>will, but weapon proficiency helps make AC more equivalent to refl and will)