The venue is running a 300pt modern tourney, I was thinking of running Odin any suggestions on the best way to use him?

Don't. Unless you just want to play for fun.
He's got a GREAT 1st clix. But if somebody hits that 19 and you are based, you're in big trouble.

The Fantastic 3. Mr. F, Inv Woman, and Thing. Ben only needs a 7 to hit you for 6 from 15 squares away. (Perplex +2 attack and TK).
Then you're a 17 with Supersenses.

Odin isn't mobile enuf to play by himself.

If you still want to play him, try and get 2 cheap pogs to tie up his ranged attackers while you move or deal with anybody that has based you. Move up and sit and wait for him to come to you, so that you can attack twice when he moves into range.

Or, wait until there's a 1000pt game in your area and load up with a bunch of Valkyries to play with Odin.

What do you think about shazam/black Adam duo and a 19pt amazon?

I think that in a 300 pt game that you would be out-actioned (i know...not a word) by your opponent. I would use the 140 pts and choose one or the other. Now in a 400 or 500 pt game, then I would love to use Shazam/Black Adam.

Thanks for the input

If you like Odin (the character) may I recomend DESTROYER?
He's kinda slow but if you keep a stealth meat shield in his hands and keep him hidden, he's a monster. just wait for your moment
and he leaves you 104pts to defend him with. some fire demons and a feat or two maybe? just brainstormin

Odin and the Turkey is 300 points. Tie up two of you opponents figures with the Turkey, go WILD with Odin... ok, it is just for fun.