Patterned is quite difficult as you need to match the repeat seamlessly for it to look good.There are pastes that stay 'mobile' for longer which help but tbh I would pay someone if it is just a few rolls HTH xx
If the wallpaper isn't too expensive just go for it... if it is just hire someone! I spent a fortune correcting my bad papering. Buy decent tools, don't paste thick or right to edges unless very thin or you'll be wiping paste ooze (sp?) from the edges and you will get it all over the paper which dries shiny. Leave plenty top and bottom to match the pattern and take your time, wiping gently with a very clean cloth.