Definitely keep shards for crafting especially wind shard, since that seems to be the most commonly used shard.

Keep doing the leves, you'll make plenty of money to gear you up when needed, and don't worry too much about gearing up really. Once you start doing the rank 20 leves, you'll start rolling the money in, depends on the available leves, and if you want to start crafting, always start off with local leves, you won't lose any shards this way.