After beating Mass Effect, you can play through the game again, with the same character, same skills, items, et cetera.
Atrakinti: Higher Levels
You can increase your maximum level from 50 to 60 if you beat the game once through and opt to use your character from the previous game in a new game.
Atrakinti: New Skills
If you beat the game and choose to replay the game with the same character, your character type will be able to learn some skills he or she would otherwise be unable to learn. For instance, on a second play-through, Adepts can learn to use Shotguns, First Aid, and other skills they were otherwise unable to use the first time through.
What's written above is somewhat accurate, but not completely. You must actually unlock specific achievements associated with weapons and skills for them to be unlocked for all character classes. For instance, for Adepts to be able to learn to use Assault Rifles, you must unlock the achievement that asks you to kill 150 enemies with the Assault Rifle.
Patarimas: Infinite Credits
Here's a great way to score infinite Credits. Follow the steps below in order to do so...
1.) First, fulfill the side quest involving Dr. Michel (from the Med Clinic) and her blackmailer. After the quest is complete, you'll get a discount from all of the goods she sells.
2.) Start selling her all of your expensive equipment. Then, travel to the Wards Markets and talk to the merchant named Expat. You can buy all of your stuff back for cheaper than you sold it off.
3.) Head back to Dr. Michel and sell off your stuff again. Repeat this process as much as you want for as much profit as you desire.