Likewise is used when you are comparing 2 similar things. Example sentence: I have been very organised this week. Likewise, I should be organised next week. Also is simply when you are saying something that adds information. I ate some cake and also some biscuits. Too is similar to also but used more casually in the context of adding to something already said. For example: Janet - I want to go there. Jane - I want to go too! Hope that helps :)

'Also' and 'too' have similar meanings (both are used to add some more info), but different positions in a sentence. 'Also' usually goes with the verb (after 'be' but before the main verb) Examples: This information is also available online. He speaks perfect English. He also speaks some German and Dutch. In speaking, 'also' can go at the beginning of a clause to give more importance to a new piece of information. It's a nice house, but it's very small. Also, it needs a lot of repairs. BUT!!! In formal written English it is better to avoid "also" at the beginning of a sentence and use "Furthermore/Moreover" 'Too' usually goes at the end of the sentence. Example: She can sing very well and she can play the piano too. Likewise has 2 meanings: 1) -similarly/ in the same way (formal use) Examples: Nanny put on a shawl and told the girls to do likewise. The clams were delicious. Likewise, the eggplant was excellent. 2) used to return someone’s greeting or polite statement Example: ‘You’re always welcome at our house.’ ‘Likewise.’ Ref: Swan. Practical English Usage; Longman Dictionary.