As a general rule, start with half of the amount the recipe calls for (unless directed otherwise), and add the spice until it suits your taste.

Allspice: cinnamon, dash nutmeg or dash cloves

Aniseed: fennel seed or a few drops anise extract 

Cardamom: ginger 

Chili powder: dash of bottled hot pepper sauce plus a combination of oregano and cumin

Cinnamon: nutmeg or allspice (use only 1/4 of the amount stated in recipe) 

Cloves: allspice, cinnamon or nutmeg 

Cumin:  chili powder

Ginger: allspice, cinnamon, mace or nutmeg

Mace: allspice, cinnamon, ginger or nutmeg 

Nutmeg: cinnamon, ginger or mace

Saffron: dash turmeric (for color)

Basil: oregano or thyme

Chervil: tarragon or parsley

Chive: green onion, onion or leek

Cilantro: parsley

Italian Seasoning: blend of any of these: basil, oregano, rosemary and ground red pepper

Marjoram: basil, thyme or savory

Mint: basil, marjoram or rosemary

Oregano: thyme or basil

Parsley: chervil or cilantro

Poultry Seasoning:  sage plus a blend of any of these: thyme, marjoram, savory, black pepper and rosemary.

Red Pepper: dash bottled hot pepper sauce or black pepper

Rosemary: thyme, tarragon or savory

Sage: thyme, marjoram or sage

Savory: thyme, marjoram or sage

Tarragon:  chervil, dash of fennel seed or dash aniseed

Thyme: basil, marjoram, oregano or savory