The first and most important thing to consider is which algorithm to use since there are so many out there, sha256, scrypt, scrypt-n, x11, x13, groestl, blake, fresh to name a few. Besides that a new algorithm could be invented and implemented. The coin also needs to have a vast social media coverage a long time before the coins launch using its main powers, For example Snowballs coin (balls) has a 13% per day interest just for holding it in your wallet. Pos coins although are a different piece of the same pie.
The first months of the coins life merchants and exchanges acceptance must be very high, this will insure the coins longevity and boost real life usage scenarios. More exposure to the coin can be “bought” by massive giveaways to raise awareness. A lot of people holding a lot of coins sounds much better than a few people holding a lot of coins. The coin must have an irc channel and tipbots in irc and all major social networks that tip miniscule or big amounts but allow offchain transactions so users can get their hands on their coins easier. This will provide more and much needed exposure to the general altcoin ecosystem. The distribution of the coin must be wide through tipbots, the mining schedule and the algorithm. Games must be created that use the coins technology and enable players to win or spend them. Games like dice, roullette, poker, betting and also seek already established game support. This will allow the coin to be used as an in-game currency for games.
The coin must have software wallets for all platforms which will enable more users to use it more easily. This is vital because lets say in the continent of Africa most people have a mobile phone and not a computer, opening up new markets for the coin. It also needs to have a complete and informative ann thread and website, this will greatly help first timers and introduce the coin to more people. Another thing to bear in mind is that a lot of online users seek anonimity for their money and their transactions, This being the reason why the coin will be needing such technologies implemented to tap into those users. The coins development team needs to be consisting of committed individuals that are willing to cooperate with other coins developers for the addition of new features or the improvement of old ones.