Your friend is having a stag do, and you're tasked with the responsibility of writing the invitations. It's an opportunity to be as creative and imaginative as you like -- there are no hard and fast rules that you have to abide by, but there are some general pointers that you should bear in mind. You can consider the invitations to mark the start of the celebrations, so it's important to give people a taste of what to expect and get potential guests excited for the upcoming stag do.
Praise the stag. The stag party is in his honour, so spend some time eulogising about how great the groom-to-be is. As he may be required to don a costume or undertake some forfeits during the event, it's a good idea to get in his good books early. It also helps to remind potential guests of what a great guy you're all getting together to honour.
Provide key information. What potential guests want most is information: where is the stag do? When is it taking place? What will be happening? How much will it cost? If you can't be exact, give a good a guess as you can. The more information that people have, the more easily they'll be able to decide if they are able (and want to) come or not.
Be creative. If possible tie in the invitation theme with the theme of the stag party. If you're going paintballing, put some gunsights on the invites, for example; if you're going on a river cruise, you might want to give the invitations a nautical feel. Even if you're not the best at arts and crafts you can print off images from the Web or use stamps and stickers as decorations.
Provide contact details. Your prospective guests need to have a variety of contact details for you or the groom, whether it's for asking follow up questions or confirming their attendance. If you don't know some of the guests very well, you might want to include links to your social media accounts (this will also help those who don't know many of the other guests start to feel included in the event).
Be enthusiastic. Sell the stag do as much as you possibly can -- if you can't get enthusiastic about it, then your guests won't either. Provide some background detail on what's happening and why people will want to come along. Overall, give the impression that the guests will be missing out if they don't attend.
Make it easy to RSVP. Give clear instructions about how to RSVP and when it needs to be done by. Once you have a fixed number of guests, you (or whoever is organising the stag do) can get on with booking venues, accommodation and activities.