Transact SQL :: UPDATE Then SELECT - Return Task With Highest Priority For A Given User

I have a stored proc which evaluates a table of 'tasks' to return the task with the highest priority for a given user - at the same time, once that task has been found - I want to allocate that user to the task. 

I have created a stored proc that works...however I'm sure this requirement /pattern is common & I would like some best practice for this pattern of update and select within a transaction.

Here is some sample data:

use tempdb;
go
if OBJECT_ID('Tasks', 'U') is not null
drop table tasks;
go
create table tasks (
TaskId int identity primary key,

[Code] ....

And here's what my current stored proc looks like;

if OBJECT_ID('pGetNextTask', 'P') is not null
drop proc pGetNextTask;
go
create proc pGetNextTask (
@UserID char(10),
@TaskID int output
)

[Code] ....