Gather, Gather, Gather. In both cases.

The number of mats for Alchemy is not that large when you figure out the useful mats. Many of them have negative aspects that are not really working as intended in the game at this time.

The big three are Bugloss, Columbine & Mt Flower. Others have benefit depending on the specific potion you're after, like Lady Smock, Dragonthorne, Blessed Thistle, etc.

I recommend using the negative mats to make all the potions you can to level up Alchemy, and then just vendor them.

You have hireling passives who can send you stuff, you also have keen eye passives that will highlight items further and further away the more points you add.

Ta ?? 9/10 after finding a rune its normally said item
....my response on finding is sarcastic.....Oh! tah...not.
I guess many will actually beg you to take them lol

But yes....just go for a stroll around the outskits of any zone and explore the wonders. You'll be falling over the stuff littered about...find hidden quests...see weird random stuff.

You'll never get many good runes deconning glyphs of any color, at least not until the next patch, and even then it will remain to be seen. As stated by others, get out in the world and harvest, harvest, harvest. You can buy mats, but as a noob, probably don't have the funds. I have never bought any mats, have leveled both enchanting and alchemy to 50.
Get the Harvestmap addon. It will help you find nodes for repeated harvesting, especially for rune nodes. All the starter islands have a lot of nodes. If you aren't finding many, maybe try a different time of day with fewer players. Pick up all runes, even common low value ones. Nodes won't respawn til you do, so not clearing the nodes hurts your chance of getting a better rune. Same goes for bait in alchemy nodes. Players consider it rude if you don't 'eat the worm'. You can destroy these items, or sell them.....bait sells well if you don't overprice. If you want more advice, search the forums, lots of info on leveling both these skills.