I understand that you have developed tanning and darkening of the skin due to sun exposure. Please do not worry. It is reversible and you will get back your normal colour.
For the second part of your question may I suggest the use of a good sunscreen of SPF 30+. I give below some tips on sunscreens:
Sunscreens are used to protect the skin from the sun preventing tanning, sunburn, premature aging, skin reactions and reducing the risk of skin cancer. Sunscreens are for topical use only. Apply liberally to all exposed skin 30 minutes before sun exposure. Reapply after swimming or excessive sweating. Wear protective eye covering. Use carefully when applying to the face. Avoid contact with the eyes. Use cautiously or avoid use on irritated skin. Do not use on infants under 6 months old. Children under 3 years should use a sunscreen with SPF of 30. If a sunscreen causes redness or a rash, discontinue use. Talk to your doctor or pharmacist about using a different type of sunscreen product. Some sunscreen products may stain clothing. Apply with caution. If you notice other effects not listed above, contact your doctor or pharmacist. If you have any of the following health problems, consult your doctor before using this medication: PABA allergy, benzocaine allergy and sulfa drug allergy. Tell your doctor of any over-the-counter or prescription medication you may take including: skin products, sulfa-drugs, tetracycline, all antibiotics. Do not start or stop any medicine without doctor or pharmacist approval. There are various types of sunscreens available in cream, lotion, gel, stick and spray form. The sun produces two types of ultraviolet radiation (UV); UVA and UVB. UVA radiation causes skin damage and skin reactions to medications, soaps, cosmetics and other chemicals. UVB radiation is responsible for sunburns and skin cancer. Sun Protection Factor (SPF) is a rating that indicates the degree of protection from the sun a product provides. Higher the number, greater the protection. An SPF of at least 15 is recommended. SPF 30 is the upper limit, meaning that numbers greater than 30 provide no greater benefit. Waterproof products provide protection after being in the water for up to 80 minutes. Water-resistant products protect for up to 40 minutes and sweat-resistant products protect for up to 30 minutes of heavy sweating. Remember too that water, sand and snow reflect the sun.