Just telling,The best spells casted are the ones which were done by heart and in which you have greatly put your emotions,faith and energy..Then it won't mattet if spell is small or big.. First Magick brings the change inside before it manifest outside.. So bring yourself in right mindset start from inner guidance and motivation then begin.. I'll suggest start with creative visualization and meditation based Magick work. Candle Magick in which you can try:
Protection,Blessing,cleansing,Good luck,Self love,Healing,purification type of spells.. Remember it's practice Don't disappoint yourself if your spell don't work at starting.. But with experience you'll grow.. And spell work for sure even if at minute level.. Because the energy sent out will work for sure. So focus on energy work too.. Meditations Chakras Auras etc will give you good experience of energy.
For creating spells I suggest you research.
Basic format I use is like when I make my school practical project file..you can skip some less important points or those are not needed..make it like you will,take hint from reading some spells online or in books and take hint from their.
*Name of spell
*Type and purpose of spell
*Date/Day/place/Time of the creation of spell as well as time to be casted on,moon phase etc
*Ingridients/Gods/spirits involved. (If any)
*Procedure of spell
(may include Chants,Hymns etc.)
*Tips or additional notes
*Observation of spell results after casting.
Still I suggest go through Books like Bucklands complete book of witchcraft.It's one of the Good books for beginners.
Ps:Sorry if my English is not so perfect.