How do future tense verbs work in Arabic?

The future tense is very easy to form and use in Arabic. Simply take the appropriate form of the verb in the present tense:

أفعل I do
تفعل You (masculine singular) do
تفعلين You (feminine singular) do
يفعل He does
تفعل She does
نفعل We do
تفعلون You (masculine or mixed group plural) do
تفعلنّ You (feminine plural) do
يفعلون They (masculine or mixed group plural) do
يفعلنّ They (feminine plural) do 

And then add the prefix "will." To do so you can use سوف which is written as a separate word; or س which is attached to the start of the verb. For example:

سوف أفعل I will do

سأفعل I will do