In the past, my de facto purchase in the beginning of the game was a Ring of Regeneration. After the introduction of Tangos, I've found people who paired them with Branches to boost their early game. While there are still some who prefer purchasing Boots of Speed as their initial item.

Early game items don't make or break the game, but it helps shape the direction you'll go. The main point is to hold your lane well, be able to regenerate without having to return to the fountain to soak up as much experience as possible.

This article was written pre-v6.50, but the adjustments have been made alongside the changes of the new patch. If you find any subtle inconsistencies, please pardon the writer and leave a note for a correction.

Also, this isn't aimed at competitive play, rather to help newcomers decided where to spend their starting money when they play their public games.

If you ever have to choose which items to be right at the get go, take these. Health regeneration is very important early game, extending your survivability, allowing you to keep in your lane as long as possible without having to return to the base to heal.

So why is NOT returning to the base important? In the early parts of the game, the main focus is to stay in the battlefield as long as possible. Leaving your lane to return to the fountain removes a significant amount of time away from the combat zone, denying you the opportunity to earn gold (by killing creeps) and gain experience.

Ancient Tango of Essification

Created by cannibals that went vegan. Allows the bearer to consume two trees, restoring 175 hit points over 25 seconds.
2 charges.

This item can earn the distinction of being the most purchased item in the game after it was added into the game. The item is cheap, contains two charges, and allows the user to regenerate a good amount of hitpoints. The best thing about the item is that it’s undispellable, so even if you get hit by enemy fire, you continue regaining hitpoints.

Why Buy?
Why not? This item is cheap (90 gold), contains two charges and lets you regain hitpoints. You can buy 3 Tangos and hold a lane and farm well, saving up for your eventual items. Almost ALL heroes can benefit from this item, even those who have healing spells – you’ll run out of mana eventually.

Ring of Regeneration

This ring is considered a good luck charm among the Gnomes, as it provides additional 2 hp per second regeneration.

Ring of Regeneration is one of my favorite starting items, although it’s popularity has waned with the addition of Ancient Tangos of Essification into the game. This item aids heroes by adding a 2hp per second regeneration rate.

Why Buy?
With the introduction of Tangos, Ring of Regeneration became less popular. But DotA introduced higher-tier items that use the RoR to make it a more reasonable purchase. Buy a RoR if you are against mass spellcasters to create a Hood of Defiance, or planning to make Mekansm (with Headdress of Rejuvenation).

This item can be made into:

Headdress of Rejuvenation

This item gives a +2hp regeneration aura per second for nearby allied units on top of a +2 to all attributes of the bearer.

Hood of Defiance

This item gives a +8hp regeneration per second to the bearer, along with a 30% magic resistance. Good item to go against a team comprising of mainly spellcasters (Lina, Lion, Lich, etc.) due to its ability to block the damage of spells.

 

Ring of Health

A shiny ring found beneath a fat halfling's corpse. Provides 5 hit points per second regeneration.

This item regenerates hitpoints double compared to the Ring of Regeneration but costs a bit more (two RoRs = 750) than wielding two of the latter. If you are playing Random heroes, you should be able to get this item quickly.

If you plan to take this item, you'll have to be careful about not dying early game to get enough money to buy this item as soon as possible. It’s also not a bad idea to purchase a Tango as a security blanket, instead of holding out completely for a RoH.

Why Buy?
This isn’t an item you can buy immediately, especially if you decide to pick a hero. You can buy a pair or two of Tangos (recommended), and then quickly pooling your money for this item. This item is a component of a lot of popular items, making it a worthy early investment.

This item can be made into:

Hood of Defiance

This item gives a +8hp regeneration per second to the bearer, along with a 30% magic resistance. Good item to go against a team comprising of mainly spellcasters (Lina, Lion, Lich, etc.) due to its ability to block the damage of spells.

Vanguard

This item gives the bearer +5hp regeneration per second, along with a 65% chance to block 35 damage. A good item for tanking heroes to carry to extend their time in battle by deflecting damage.

Perseverance

This is the ultimate regeneration item, giving 100% mana and +5 hp regeneration for the bearer by combining Ring of Health and a Void Stone. A very versatile item that can be made to future, higher tier items.

Flask of Sapphire Water

A canteen full of the purest, bluest water. Heals 400 HP over 10 Seconds on a friendly unit. 1 Charge. Dispels on attack.

The Flask is a good item to regenerate a lot of HP in a short amount of time. However, they lost their popularity after the introduction of Tangos, as Tangos are undispellable.

Personally, I sometimes buy this item when I have some extra money and anticipate a lot of heavy nukers. His way, I’d be less afraid of being finished off by an unexpected nuke coming my way behind the tower.

Why buy?
This isn’t really the most cost-effective item --- consider it more of a security blanket. This item heals a significant amount of HP in a short amount of time, useful during instances when you fear an ultimate from Zeus, or a gank that can take you down in one hit. If you can keep yourself with decent hitpoints while laning, you can just get purely Tangos instead.