Here are some tips on how to be successful on Howrse. If you have any more tips, feel free to PM me so I can add them to this list. Please feel free to copy and share!
(1) Stroke a horse in the Safe Haven (click) for a surprise.
(2) Stroke five Xanthos divine horses (click, click, click, click, click) for a surprise.
(3) Answer Archimedes's question correctly (click) for an Aging Point.
(4) Congratulate five Topaz divine horses (click, click, click, click, click) for 150 Equus.
(5) Defrost Frost (click) for a chance to win Frost.
(6) Watch videos from Howrse sponsors to earn free Equus (click); because of this your expenses should never be more than your earnings.
(7) Participate in Creation Space voting when available (click) for Equus.
(8) Name any horses you don't mind losing Junior Croesus. Each month one horse named Junior Croesus is turned into a Croesus divine (click).