It is no problem to let the bot quest your first character to level 30. Your gear can be lousy and still make it to level 30, just don't sit and watch your character die.

By that level, you should have most of the locations you need to do a gathering skill to level 50. I recommend doing botany to level 50. If you just let it run and you undercut the market on everything you gather while leveling your botanist then you should be able to buy good enough gear to continue to level botany all the way to 50. If you see your character frequently "fail to obtain" (such as 1 out of 3) then you know you need to upgrade your gear. I upgraded my botany gear about every 10 levels.
Different servers have different supply and demand issues. For example, my server had a high demand and high prices for mahogany lumber for a while. But, shards will always sell on every server. Set your botanist up to do shards at first. At level 50 it will take you about 17 hours to gather 12,000 shards (about 700 shards per hour). Then, you can sell them for 60-65 gil each and have 720k gil to beef up your main class and be on your way. After that, you need to pay attention to the market on your server and figure out better ways to make gil. If you continue to flood the market with shards the market won't last very long. Furthermore, if every botter did shards we would be easy marks for bot hunters to video us and report us.
If you choose to make a miner/goldsmith you will discover that silver ingots sell very well (they currently sell for about 6k each). They are needed for glamours.
As you work your way up in the crafting market, you will find things that sell for 2 million gil each and more.
A lot of people say Goldsmithing is the best class to make money, but I have found Carpentry to be quite lucrative.