Fast ways to level up!

mass evolution of pidgeys, weedles, caterpies, etc. using a lucky egg, and hatching multiple eggs during the same period.

Assuming you're a new player, use the Lucky Eggs you earn through your levels when you have half an hour to spare exclusively evolving Pokémon and have gathered at least 60 that you can evolve. (This is assuming you'll get some new mon out of evolving - in reality you should be able to evolve 80-85 mon during a lucky egg).

Favorite all the mon to be evolved so you can count them up. You can clear the favorite star after each mon is evolved so you won't waste time searching your bag for each, as they'll be right at the top.

Lucky Eggs are practically irrelevant post-level 30 - this is coming from a player who is reaching 40 in about a week. But in the early levels they're very significant, so make sure you make the most out of every single one.

Pidgey, Caterpie, Weedle are the easiest to evolve (12 candy each, you get one back after evolving so you can count 11 for each past the first one). Rattata, Sentret, Ledyba, Marill are also fairly easy at 25 candy.

As others have said, depending on the biomes around your area some mon will be easier for you to get... for example, if you get lots of water mon you'll be evolving lots of Poliwag and Horsea which are also 25 candy; for grass areas the commoners might be Oddish and Bellsprout instead.

I find it surprising that people answered such broad question. The OP could have googled the topic, then asked specific questions about the issues that came up. A much better way to use a forum imo.

As a fellow noob who is level 25 after four weeks of playing:

1) Do the lucky egg mass evolutions that others is mentioning.

2) Try to do the lucky egg mass evolution on day 7 of your streak which gives you a big bonus.

3) If you can, time the hatching of a number of eggs at the same time as the mass evolution. Even if you don't do this, there's a lot of value in hatching eggs. If you are willing to pay, egg incubators are pretty great.

4) Never miss a day! You need the streaks.

5) Set a daily goal. During my second and third week playing I had a goal of 25k xp just grinding pokemon. This is not counting mass evolutions.

6) This has nothing to do with xp gaining as such, but hold off using your stardust and evolving the really strong pokemon just yet, you'll thank me later. You will rarely want to power up a strong pokemon that is less than level 20. Focus on evolving basic pokemon until you reach a decent level.

7) To make grinding less boring, try to go to new places. I live in a small city with only one small area with pokestops. I am so jealous of people in cities who can go to various places. If you do live in a city, take advantage of it.

Bubblestrat is still the fastes way to level up!