Disclaimer: I pretty much suck at MtG and am just a hack, but....

Seems that most lifegain decks need to lay down a defensive/deterrence barrier before bothering about gaining life. Therefore most Selesnya decks include a few staples, such as Fleecemane Lion, Garruk's Companion, Loxodon Smiter, or Hornet Nest etc ; big cheap-ish hitters/blockers. Also, if the budget can extend that far I like Ghostly Prison or the less effective Norn's Annex.

Check out some lifegain decks for ideas; a good one is Headers13's (http://tappedout.net/mtg-decks/h13_sel/); yeah I couldn't get the deck's slug to work.

Also, like it's been mentioned earlier, Wall of Reverence is better than a bunch of little Enchantments etc which give you one or so life points. I understand they were included to help Ajani's Pridemate, but you said that didn't work out so well (WoR will give you exponential life, which rocks...if it survives, which is its biggest problem). A cool combo getting around is Heroes' Reunion + Voracious Wurm = 7 life + 9/9 Wurm for 4 mana. Sweet. Also, it costs a bit but Sunbond (especially if Wall of Reverence is out) rocks. Oh, and Rhox Faithmender is nice if you can afford it.

As for card advantage (i.e. drawing more cards) I'm not too sure... Inspiring Call maybe...?

But I'm fairly inexperienced and so recommend taking this advice with a huge dose of salt.