I can't believe you wear steel toes working outside in the summer. I have a hard time with them and I always opt for CSA compliant composite toes. Reason being is if you're outside long enough the steel heats up and that's just not fun but granted you do this as a career while I only do that for the summer (and I admit I might be a bit of a pussy).
As for what to wear. Just make sure you don't show up like a speedballer and you'll be fine.
If you want to try the PMC look then you could try it with what you have. Make sure you can deal with them getting dirty (the kind of dirt that never comes off) or ripped.
The PMC look is pretty wide in terms of what you can do. Boots + Jeans + black/green/tan top. or you can wear polypro "climbing trousers".
I have a pair of tan trousers like this
except the mens version.
If you do that plus a OD softshell top or something you'll be pimping.
As for footwear, I know a lot of recball players will wear runners and stuff but at minimum please wear those crosstrainer/hikers like these
and also perferably in a neutral tone.
Workboots are fine but not really designed for running and like I said above I find steel toes just plain suck and if you have composite then you'll have fun all day.
Hiking boots are much better since they're kind of designed for running/moving fast. In fact that's what I use. I got a pair of McKinley's (dark brown) for something like $90 on sale probably 5 years ago now. I might get some new boots at the end of this season just cause my current ones are 5 years old and starting to fall apart.
Military boots however are the ones you really want (if you can afford it), they're not terribly expensive though and there's always the option of buying surplus from surplus stores. One of my friends snagged a pair of really good boots for something like $25-30.
That's it for the first day..... A vest or belt would be an asset but you can always borrow on your first game just make sure you ask around before and tell people you need a vest. Otherwise just rock 2 or 3 midcaps and stash them in your pockets, nothing wrong with that but I would have a problem if that happened in a milsim game. If it's just a regular "weekly skirmish" then all the power to you.