So my cousin (Cousin's husband actually) recently msg'd me on facebook asking about some workout and diet (sorry... i should say "nutrition") tips. He's a mid 20's thin build guy looking to bulk up but hasn't been in the training game for long. Now I'm not saying I'm an expert by any means but I do try to offer unbiased advice as much as I can and always promote a natural, predominantly whole foods approach where possible. Here's what I suggested:
Hey Cuzz! Yah man I can definitely help out. Let me know what you're doing for meals. You'll need to bump up ur overall caloric intake but make sure they're quality calories from lots of whole foods. Try to stay away from refined foods. Lots of carbs (oatmeal, potatoes, brown and basmati rice) and protein and a moderate amount of healthy fats (from things like olive oil, eggs, nut butters, etc).
Protein should come from lean sources like chicken, fish, and definitely beef (high in B vitamins and for some reason it really helps kick up ur testosterone). Make sure ur taking a good quality multivitamin too.
Since ur starting out i'd say stay away from spending ur money on protein and weight gain supplements. They're great for helping to put on weight but i personally think they should only be used once you've got ur real meal plan on track. If u go to a (insert big retail "nutrition" store name here) i guarantee they'll try to sell u everything under the sun promising to help you gain weight but trust me... they work on commission and want to make the sale (i should know... i used to work there. haha)
With regards to weight training, stick with heavy compound movements and make sure ur doing the movements properly before adding more weight. Lots of guys starting out try to do too many fancy moves they see the bigger guys doing but they forget about the basics. Base ur workouts around bench press, squats, and deadlifts and i promise you'll notice a difference in ur strength right away. Dude i've been training for almost 20 years (damn i feel old!) and i still do those movements. If you want, email me ur current workout schedule and i'll take a look at.
This is kinda the tip of the iceberg so let me know if you have any questions and i'd be happy to help out. Also keep me updated with ur progress!