Ive been into the hobby for a few months and have been painting my men myself but I was wondering if some won could give me a few tips on how to highlight and shade. I'm primarily painting uruk hai so some tips on painting them would be helpful too.

There are a few schools of thought on that, so each person would have different ways to do it plus which colors in what order.
Basics though;
Each color has at least three zones.
1 - base color
2 - Shade color
3 - highlight color.

You can have any number of steps or transitions between those zones.

So first pick your base color. with uruks I would suggest either Doombull Brown or A 50/50 mix of Rhinox Brown and Troll Slayer orange. apply several thin layers if you can. as you get better with this step you can create transitions win this step with how may layers you apply on each area.

Then you will want to shade the areas that will not receive light, to some this is any non raised area but that is not accurate but can work. Mix your shade color with water or thinner and wipe off access (usually on a figer holding the model) and apply only to the area you are shading. again, you can apply more thin layers to the deeper area's to create darker shadows. AS you get better you can apply contrast colors in glazes to you shadows also, but for now just apply your shade color. For uruks I would suggest Rhinox Brown for either of the above base colors in previous step.

at this point fix any spots you messed up in the shade step by applying your base color again.

Highlight. Pick a highlight color, for many this is as easy as mixing a lighter color or different hue of color with the base color. I would add either Ushabti bone or Troll Slayer Orange for Uruks to my base color in a 50/50 mix. Add water again to thin. Apply this in layers on just the area's that will receive the most light. Again for many this is any raised area of the model which can work but is not accurate. Build up a few thin layers and you will be fine, fix any mistakes with your base color as you go.

To highlight further you can continue adding lighter colors as you feel comfortable or shade deeper as well.

This is the basics. I highly recommend reading an article or watching a tutorial once per week (or more if you can). Regardless of the skill level or colors they are teaching, it will slowly improve your thoughts and skills on the process of painting and other aspects of the hobby.
check out many articles at these links;
cool mini or not
http://www.coolminiornot.com/articles/5 ... cles-Index
the One Ring
kb.php
Tale of Painters
http://taleofpainters.blogspot.com/
Storm the Castle
http://www.stormthecastle.com/index.htm
Miniature Mentor
http://miniaturementor.com/

For starters anyway... there are hundreds there but hundreds more to be found. Never stop learning.

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http://www.sithious.webs.com

For Uruk skin I use:
Doombul brown. Base
Nuln oil. Wash
Doombul brown mixed with ushabiti bone. Highlight

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In a hole in the ground, there lived a hobbit.