How do you form the present participles of French verbs?

Answer 1

The trick is to start with the nous form, then drop the -ons ending and add -ant.

Examples:
Manger - nous mangeons - mangeant
Venir - nous venons - venant
Boire - nous buvons - buvant

There are only three exceptions to the rule:
être - étant
avoir - ayant
savoir - sachant

I find the exceptions pretty easy to remember since être doesn't end in -ons in the nous form, and "avant" and "savant" (what you would get for avoir and savoir if you followed the rule) are already words.

as an adjective

Answer 2

In French, the present participle of regular verbs is formed by taking the infinitive form of the verb and replacing the -er ending with -ant, -ir verbs replace the -ir ending with -issant, and -re verbs replace the -re ending with -ant. For irregular verbs, the present participle must be memorized as there is no set rule.