How can I get my cousin to come visit me from Guatemala?

No actually, you don't need a letter from a lawyer or you don't even need a letter of invitation from the guest host, which would be you. What your cousin needs to do is to establish proof to the US consulate in Guatemala City, that he has sufficient ties to that country that will convince the consulate officer interviewing him that he will return once his visit is complete. Now the way to do this is to submit tax returns of a three or four your period, showing his employment history. It would be advisable to get a letter from his employer showing his rate of pay, the number of years he's worked For that employer, the fact that he's a very good employee and he's going to continue to work at the company. Another good thing is to show if he has any property or if he doesn't own property, then he should provide a lease that he's paying rent on, and how many years has he been at that place where he's renting that would also be a good idea to submit. But if he does own property then he should submit a copy of the property appraisal report which shows the net equity in the house, which would be the market value minus the mortgage on the house. So if he wants to get an expert appraisal for the property he owns that also would be a good idea. Hope that helps.