This is quite a usual question for beginners and is one that I have had the experience of sales and contacts to help me answer; although I must point out that I don't herald myself a spinning expert!

I always recommend that beginners try the following base fibres in their spinning...

Base fibres
Merino - it's soft, fine and comes in so many colours.
Blue Faced Leicester - A little coarser than Merino, but still super soft. The staple, or fibre length is also longer than Merino, so is preferred by some spinners for its strength and ease of spinning. This mostly comes in natural shades.
Shetland - Similar to Blue Faced Leicester in its natural form, Shetland has strength and warmth to its feel. Its natural shaded fibre is also very easy to spin with.

Once you feel you have gained enough experience to try blending or effects in your yarn spinning I recommend the following fibres for beginners.

Blend Fibres
Alpaca - has a longer staple giving weight and strength to your work. It also has a silky colour appearance, although not as soft as wool.
Tencel, Bamboo, Tussah and Mulberry Silk - these are wonderful blending fibres for spinning and will help give your blend a lift with some shine. The fibre is easily worked into your yarn either as one of the plys (2 or more plys), or as a hand carded blend running through your wool single ply.

Effect Fibres
Bamboo and Soya Bean Staple - add a nice slub effect, they can be quite tricky though so the key is to slow down your spinning speed to make sure you catch in these fibres.

I hope this helps? Please feel free to view my shop here on eBay for the fibres you may need.

Sara.
Sara's Texture Crafts.