The formulas [per piacere] [per favore] [per cortesia] are not used as instinctively in Italian as they are in English. Usually a smile or the conditional tense of the verb are enough, for example: [mi spediresti questa lettera?]. To invite someone to your house, you could say: [fai un salto da me domani] or [venga a trovarmi appena ha un momento]. To invite someone to do something with you, you could say: [ti piacerebbe andare a vedere un film?]. To offer someone a ride in your car, you could say: [posso offrirle un passaggio?]. To invite someone to dinner, one possible way of asking would be: [perché non venite da noi a cena uno di questi giorni?]. All of these questions usually receive answers such as: [sì! grazie] [accetto volentieri] [vengo volentieri] and also [sì, sarebbe bello] [ottima idea]. If you would like to be more formal, you could say: [è molto gentile da parte vostra]  [ci farebbe molto piacere].

To offer something,  such as a seat or a drink, in either a formal or an informal way, the most important word is [prego]. Usually, one does not accept the offer right away; at first, a refusal is to be expected. Only after the offer is repeted once or twice does the person finally accept.

To refuse an invitation or offer, you could say: [no, grazie] [io no]. Also, to refuse going to someones house or meeting them to do something, one could say: [no, grazie] [sarà per un'altra volta]. Or, on a more formal level, a possible response could be: [per quanto abbia fatto il possibile per liberarmi . . .].