There's a major emphasis on buffing my creatures with enchantments such as Gaea's Anthem and Spear of Heliod, and on top of that there's a decent amount of counter generation. I want to be able to make better use of those mechanics by filling my board with as many creatures as possible. I want to achieve that by token generation, of which I have some, just not quite enough.
Populate is an extremely meh mechanic when your tokens are 1/1 humans, even with Sigarda making them 1/1 hexproof humans. It gets much better when you have things like wurm or eldrazi tokens, or token copies of real creatures, but it's a waste of space if you're just copying 1/1s.
As far as making the humans in the first place, there aren't a ton of great options. Increasing Devotion is probably the best one-shot effect for human tokens, and if you have any clue generation Ulvenwald Mysteries isn't half bad. Thraben Doomsayer and Commander's Authority both give you 1 human/turn (although Commander's Authority is way more expensive than it ought to be on top of being an aura).
You could also look at ways to stock your graveyard so that you can make tokens with your commander. Life from the Loam is a pretty awesome card in most green decks.
Lastly, consider branching out from just human tokens. Saprolings and Soldiers both give you a ton of additional options for token generation.
Assuming you are okay with non-human tokens, you might consider Spirit Bonds. Having each of your humans come into play with a guardian spirit to protect it feels like something Sigarda would probably like, and being flyers, spirits are more useful than most 1/1 tokens. Geist-Honored Monk brings some spirit tokens and gets bigger based on the number of other creatures on board.
I'm trying to stick to mainly human tokens, but others like Soldiers work well with what I've got. Spirit Bonds might not be a bad idea. I could always use more creatures on the field.
If you're willing to do Soldiers, Mobilization is an excellent mana sink, which also gives you a second source of mass-vigilance after Intangible Virtue.
My deck is Human tribal with Sigarda, Heron's Grace as my general.
http://tappedout.net/mtg-decks/14-02-17-sigarda-human-tribal/
There's a major emphasis on buffing my creatures with enchantments such as Gaea's Anthem and Spear of Heliod, and on top of that there's a decent amount of counter generation. I want to be able to make better use of those mechanics by filling my board with as many creatures as possible. I want to achieve that by token generation, of which I have some, just not quite enough.
Cards I've already got in mind include Parallel Lives, Hour of Reckoning, Intangible Virtue, and Growing Ranks.
~~~Just as a side note, I'm trying to keep the deck as cheap as possible, although I am lenient enough to not consider it to be exclusively budget.
MAJOR EDIT: I've decided to drop the human aspect of my deck and go fully into token generation. I've swapped out Sigarda as my general in favor of Tolsimir Wolfblood and I will eventually go for Rhys the Redeemed
New decklist: http://tappedout.net/mtg-decks/tolsimir-token-generation/
Instead of populate, look at things like Rhys the Redeemed, Parallel Evolution, and Second Harvest.
As far as making the humans in the first place, there aren't a ton of great options. Increasing Devotion is probably the best one-shot effect for human tokens, and if you have any clue generation Ulvenwald Mysteries isn't half bad. Thraben Doomsayer and Commander's Authority both give you 1 human/turn (although Commander's Authority is way more expensive than it ought to be on top of being an aura).
You could also look at ways to stock your graveyard so that you can make tokens with your commander. Life from the Loam is a pretty awesome card in most green decks.
Lastly, consider branching out from just human tokens. Saprolings and Soldiers both give you a ton of additional options for token generation.
Two Score, Minus Two or: A Stargate Tail
(Image by totallynotabrony)
Two Score, Minus Two or: A Stargate Tail
(Image by totallynotabrony)
Are all great with the soldier token themes, Cathars' Crusade is also great.
(W/U)(B/R)GForm of Progenitus, Shape of a Scrubland
BRGJund Tokens with Prossh, the Magic Dragon Foil
URGAnimar, the RUG CleanerFoil
RRRFeldon of the Third Path 2.0 Foil
BG(B/G)Not Another Meren DeckFoil
UR(U/R)Mizzix, Y Control and X Burn Spells
(W/U)(B/R)GHarold Ramos - The 35 Foot Long Twinkie (In +1/+1 counters)
UB(U/B)Dragonlord Silumgar