What should I consider and look for on Tour of Duty?

I have used TOD and did two years on Active Duty with the National Guard Bureau. Once you get selected for a position your packet will get routed through your State and you will have to have a packet completed before that. When you unit gets you all of the required documents your G1 will release you and you will get orders. You don't have to tell your unit that you are applying. It is more of a courtesy. When you get selected you will have to have notify them. They don't have to release you even if you get selected.

As your in the guard, sometimes units do not allow their members to seek additional tours. I had a extra deployment all set up and then we got the First Oil War. Guess what, I didn't get to go. Anyway, I'd start with your full time clerk and see what he/she has to say on this first. Then I'd start checking to see what is out there for your MOS. Also, don't forget to see if you can snag a school.
School always helps for promotion. Your tech can help on both of these. Read the other comments here, they are all great.

Lastly, you're young, so if you can get a tour, go see the world.

Ive used tour of duty once but did not get selected. When i applied for the position i dint ask for permission but you need a couple documents from your COC. When you set up the profile/ apply it asks you what you need and have to upload it. What made you wanna deploy again?

While the processes have been described well, there is more to consider. Number one Commands have reintegration policies that cannot be averted, on top of that they can determine that it is not in your, or there best interest. Finally, you will learn this soon, do not take Family time for granted, there will come a day that you may regret your decision for one reason or another as it relates to Family. I always told my Soldiers, and those I continue to mentor today, you will have multiple opportunities to deploy throughout your service, take the valuable downtime to prep yourself for the next promotion, assignment, and yes life after the military. Finally and maybe most important, be careful what you ask for.

Increase your chances by becoming a NCO, make that your next goal also considered changing mos giving you an secondary mos to better your odds

With a deployment you now have real time toward your GI Bill vesting.

Focus on just getting any amount of time on title 10 orders regardless of duty and place and secure that 100% GI Bil. l

The only 27D jobs on TOD right now are 90 day stateside activations or senior NCO positions.
There are 00G (non mos specific) jobs for lower enlisted but they were stateside as well.

Your profile says you're in the national guard so you'll need a TAG release letter / state endorsement. This is a formality but it can take some time to get so bring it up with your chain now. Build a profile on TOD and upload all the needed documents so you can apply.

One of the issues with TOD is you currently have to be on a government computer to access it. Hopefully you know someone with one who can check it for you daily for new positions.

Other places to look for positions are on the unit vacancy listings on S1 Net. As well as pfi.dod.mil.

Best of luck