Congratulations, learning OB is very good for their behaviour and relationship with you.
I use Devon as treats when training http://en.wikipedia.org/wiki/Devon_(sausage
) not sure if you have this in the states, but anything like this which is not spicy and very soft is usually attractive to them. You don't want to use treats that are hard requiring a lot of chewing as he will spend too long trying to chew the treat than concentrating on you, so chose something easy to chew and swallow.
For his focus on you, just practice using treats. Have him in a sit and with a really yummy treat in your hand, wave it in front of his nose, give the command to 'look' or 'watch' then bring the treat up to your eye. The second he looks at you, mark it and treat him. Eg when he looks at you, say 'yes' or use a clicker and click then give him the reward. Keep practising and you will eventually be able to get him to look for longer periods of time and immediately on command. This command and a recall, imo are essential as there will be times you may need to distract him so if he knows the look command this will help you.