Going into screwing yourself, there are some things that can be done in character creation that just can not be recovered from. This is now World of Warcraft where classes and races mix all in the back ground and bad combinations are disallowed. It's not even Everquest where stats didn't matter as they could be fixed later on. There are two things you are going to need to know for character creation, 3.5 edition mechanics and DDO particulars. The game is very close to 3.5 edition D&D so knowing it is a help. The particulars you will learn from play but enhancements and a single mana bar is a pretty huge change from pen and paper. I would suggest you try for a barbarian and just play asking questions. Take on of the suggested paths in the character creation and you should be OK.
Another aspect of the inequity of characters comes with races and character build points. For the most part the races are pretty even. Yes there are races that work better for particular classes which is something you should think about but generally they are the same. The Drow is not, it is statistically better than others. To make up for this the game creators require you to play a bit before they allow you to play the drow. The mechanic used to unlock this and many other perks is favor. Completing quests on higher difficulties give a one time favor award that is tracked. When you hit 400 total favor you can play drow. This is usually pretty easy to reach maybe 7th level if you are slow. Then you can start playing your new drow character, which i generally don't recommend. If you are having fun with your current character i say keep playing. Part of this is you get further rewards at 1000 and 1750 favor. At a thousand you can start creating new characters at fourth level. At 1750 you gain the ability to create new characters with 32 build points all except drow. Now you may consider restarting a new character. In the beginning you only had 28 point to create your character this extra four is a huge help.
Flowing from this is the idea of the TR or true resurrection character. D&D online doesn't constantly throw new content on top of the game. Instead of ever increasing levels they have created a system where high level characters play through the game again to get more power. This is the true resurrection or TR character. New players will often seen a massively over powered character in their party zerging through the entire adventure, this is probably a TR. To become one of these TR characters you need to hit level 20 and then run epic level dungeons. In these dungeons you gain tokens that allow you to purchase a item that allows you two perform the true resurrection. These are the hardest quests in the game so you will fined they are pretty hard for your now 20th level character. They get easier once you have completed at least on TR. The reward for TR's is an increase in build points for the next life and an extra past life feat. You will have 34 build points on your first TR and 36 on your second resurrection of the character; 32 for drow. The past lives are a big help and everyone can use barbarian past lives for more Hit points.
The final component to your power is equipment. You will have a natural growth in power for the most part but there are three sorts of items that are key to a powerful character. Powerful items in D&D are not necessarily statistically better than other a lower minimum level is often much more of a factor. Named items that you get in quest or as end rewards are often the best help early on. Another thing you need to look for are quest chain rewards. Often you have a series of four or more quests that don't give rewards until you have completed all, but the rewards are special named items. Keep an eye out here for the regular weapons and armor in the list. These often have very low required levels and are the true reward. If you get something with a level two requirement you may be able to zip through the early levels on your next TR. The final piece to this power puzzle are green steel items. These are going to be your bread and butter for much of the game. You need to run quests in the vale of twilight to begin thinking of crafting these items. So you are going to be at least 16 really 18 as you need to run the shroud to complete this stuff. You are going to need to run the shroud many many times to get all the bits you need but the end results are worth it. Green steel are super powerful items that have a minimum level of 13. So you will be able to make use of them when you TR. There are many crafting tools on the web, i usually just go here. The lightning 2 and Mineral 2 weapons are pretty powerful as are items that give extra hit points.